I use a lot of references for inspiration, then I just imagine what angle I need to put the camera in for a good mood and off we go. I learned a lot about vanishing points and perspective to improve them more and more ... I still don't like doing them, but bakcgrounds are just mandatory to create the right atmosphere in a scene.
Not to mention that they show the readers where said scene takes place.
i usually try and do different angles to keep it interesting, and yeah at times i can miss details but you got to trudge through the thickest stuff sometimes to get places
I think an easy way to solve this is to just go look at interiors, in movies, TV, or even just Google Images, and pay attention to what you find. Save pictures to reference/trace later if you have to; it's allowed. ^^; I mean, if you don't know what to add to a room, you won't suddenly start knowing if you don't go and get that knowledge.
Here's a nice one I found on Google. You can see a lot of basic living room elements, including the houseplants you mentioned. But besides the archetypal couch+carpet+coffee table, there are plenty of decor items to take note of.
The little side table with the lamp, the table in the back with the more traditional lamp (and other little knickknacks) that hugs the wall, the well-placed picture frame up above it...the auxiliary chairs that help fill up the space and help define it as a 'sitting area'.
And if you look closer, there are smaller accessories to notice too. There are books (or at least book-shaped items) on both tables, and all the houseplants are varied in size-- some are big enough to take the place of furniture, and some are tiny enough to sit decoratively alongside the books and lamps. There's also a few more random items in there, like the basket, and that thing that looks like a candle on the table.
Random character-related items are also an important part of room-building...although that alone is no substitute for knowing how to furnish and decorate a room. Maybe your character is a mercenary who leaves weapons and maps lying around, or maybe they're a student and they've got textbooks and sticky notes all over the place. But it'll look more natural if all their clutter is lying on top of tables and chairs and hanging off shelves, rather than just scattered across an empty floor.
maybe until I learn how to use CSP properly I will continue dying every time I draw bgs in SAI (at least Im used to draw this kind of architecture)
still have to do some research and take references cause yeah, I wish I would avoid bgs/enviroments as much as possible but the most I can do is to use them in key panels?? and everything ends as walls and trees at the end xD
I have just seen this and I literally spent all the afternoon doing this 
I take reference on pinterest photos but furniture magazine can also help a lot for more casual backgrounds. Just think about your character's personality and the kind on places and enviroments he moves on. In this case, for example, I had to draw the palace of a prince of hell considered the greed demon, and I take influence on ancient egypt to draw him. He also loves cats, so cats are like gods on his country - then I search "egyptian houses", "pyramid", "gold", "bastet statues", "egyptian furniture", "egyptian hotels", etc, etc and I play with gold too to give it the vibes of the demon. I think on how people lives there, what kind of people lives there, what they do,etc.
Sorry for my super-long comment but I think it can all help? 
For interiors, I highly recommend using a variety of reference photos for ideas as to what to put in them. Drawing a background from reference is something I usually find pretty enjoyable, honestly! I never used to, but then I set aside some really focused time to practice them, and now they're deeply enjoyable.
I also use simple, custom 3D assets for my comic, to help with speed and consistency. They're very basic - I drop them into a panel and just trace over them. While I can use perspective grids and such, this saves me a lot of time, and speed is essential with comics.
I'm sorry, I gotta help you. SAI Paint Tool used to be my go to for digital drawing. Then for bubbles and dialog fonts I used Adobe CC.
CSP is where the buck stops! It is miraculous. Easy to draw lines (the sensitivity and stability is so much cleaner)! Then the selection faint ... it's amazing...once you've selected there's a transparent type of small strip of menu where you select bucket right away and it fills that area. There's no "back and forth". It takes away all that PAIN! And you don't have to be in the correct layer to select those areas!!!!
I'm not young and it's hard to learn something new. I took a long time to dive into CSP, but ohhhhhhhhh, I canceled my Adobe Plan, I've stopped using SAI...Try it! There's tutorials on YouTube, but if you have questions, this newbie is glad to help!
BTW, you do beautiful backgrounds!
I had to stop doing backgrounds. My health took a dive so I hired an amazing artist to help me. The tool that is used is Sketchup for Interiors or buildings...CSP is used for painting bgs. I used to do mines in the painful manner (with little success) of inking, using refs, or nearly banging my head.
Photo refs is mostly what I used in the beginning. But now I have my artist. I just give the concept and thumb sketches then it's created with dazzling results:
So for anything plants, I highly recommend using a brush that just deposit's leaves for you. It looks more stylistic than realistic, but man, it's a comic, and it's worth it to just bust out leaves whenever you need because house plants are a wonderful way to add life to a room.
Other than that, something I learned and something I live by with interiors is to avoid doing 3 pt perspective as much as possible. Most of the time you only need 1 pt or 2 pt. So much easier when you can use the shift key to draw either horizontal or vertical on edges of picture frames and walls. Plus, it's pleasing to the eye. One of the bigger issues with 3d renders is that they are too perfect, so I'll actually switch to isometric rendering because the rendering on a 3 pt room is a little dizzying (unless dizzying is my intent)
For objects to put into rooms, can't go wrong with clutter that matches an already established interior design style. So I got a bear that studies human history, so decorates her southwest home with pottery because those things have meaning to her. I also gave her home a warm color scheme which helps tie in the places where I don't have knicknacks, because you don't need to have every inch covered, but just enough. In the end, the warmth and the oodles of plants show that she's a bear that likes to take care of things. You can do a lot of worldbuilding about characters from what they choose is most important to display in their home.
adasfadg thank youu
I know its really good and Ive used it mostly for illustrations than comics and many of the csp yt vids Ive watched havent helped much (since msot of them skip the parts I actually want to know and lately been relying on Twitter CSP users when they find something lol) plus, still the brushes doesnt satisfy me for the actual comic but I would have no problem with them for the next one
Probs Ive said this before in other threads but since Im used to draw bgs analogically it frustrates me to take time fighting with the csp 3D assets at the moment and its faster for me to draw them from scratch but definitely Im gonna need csp for my next story. I have too many complex bgs I need to prepare beforehand or Im gonna die XD (hospitals and labs. So far Ive been discretely taking pics every time Ive been at the hospital the past year xDDD )
And thank you for the offer!! 
I draw bgs for vns sometimes so I feel the sentiment so much. Since I'm pretty burned out from that I'm experimenting with prioritizing shapes, composition, and story/purpose (without the latter it's way more difficult) instead since I never got into using 3D, and detail only where it needs to be.
Aside from the reference tips... I've usually broken down interiors into structural elements, furniture and objects on top of it into either functional or decorative items. Then categorize those further by thinking about related objects and quantity depending on the purpose of the room. Something I was reminded of recently is that detail = more visual information so maybe adding embellishments to furniture, props etc. by means of changing shapes a bit, patterns, texture marks or other graphical elements is one way of tricking the eye into seeing a lot more than there actually is.
Thank you so much. IMHO, you already master inking the architecture and rendering the landscape. I'm glad to hear you know a lot about csp. TBH, I've never used csp 3D. So I'm a baby there! 
Keep up the good work! (Oh, those hospital pics, I think, will come in handy for you.
Luv n hugs, Cathy
This shit took me weeks. WEEKS. I literally hated everything during that time, and it's still incomplete in some parts since I just cut those out in the comic (I'm telling you, I hated everything, I was almost quitting my comic over 1 room). You can see bottom right side is.. well.. you can see.
I used references plus edited some pics I've found for some furnitures.
These two are the final usages of the room
I use a ton of references- some 3-D and some photo.
For this page here, I looked some photos of clocks, a baseball jersey memorabilia framed content, bed headboards, a shower stall, shower knobs and shower heads, a table, and appliances. It was a challenge, but I was happy with the results...
This page, I had to look at photo refs of school lockers, and high school hallways...
As others have said, references and perspective grids are game-changers. Remember, your characters live in the environment, try putting the perspective grid down before you draw them.
Perspective grid generator: https://www.reubenlara.com/perspectivegrid/5
Offline perspective grid generator: https://haztro.itch.io/perspective-grid-maker1
References are highly HIGHLY useful. For every page I draw, there's probably something I've looked up on google prior to drawing it. Street view on google maps can put your feet on the ground almost anywhere in the world, and it's one of my best resources for outdoor references.
The more lush your environment, the more expansive your world will seem, and the more immersed your reader will be. There's nothing like a really busy city shot that makes me wonder what's happening just around the next corner. Usually when I'm writing, I dedicate a paragraph describing in detail the environment the characters are in for the establishing shot first, before the characters do anything at all. This usually results in them interacting with their world in a more realistic way and gives me a really solid idea of what to draw back there when the time comes. Your environment is an essential part of your storytelling. I've seen a lot of writers write characters info-dumping because they're proud of all the work they put into their worldbuilding, but it's unnecessary if you draw it all into the panels, or if you think about how to reveal information purely by your characters interacting with their surroundings. It builds your world and keeps the focus on your characters at the same time.
All that said, @jermajay I think your backgrounds are great as is. I like how your backgrounds drift in and out of your panels, it gives your panels a narrative to illustrate how your characters are more focused on something more internal, or each other. I like the little character building details like the fashion photos, or the spider-man ball, but your backgrounds aren't super busy either, which might detract from your characters. You've got a good balance here, good work!
