NEVER go with your initial character design! Have you SEEN what Shrek looked like in his earliest stage
4
oh my.
One point I might add though, in case you are talking specifically about creating comic/manga is that you need a HUGE fundamental amount of knowledge of (not anatomy or technical stuff) the area you are writing/drawing about. For example, if you want to write some doctor or scientific story, even if it's not your main focus, you still need to do some intensive research into the field (or the so-called 'material gathering' for mangaka) and see how it actually is to make your plot convincing. Even if the readers are not familiar with it they can still point out flaws and plot holes.
And beginners really don't think much about the commitment they are going to have to pour into their series, I made that mistake before and they either cry and bear the pressure or just give up entirely. (glad I'm not the latter)
I think the biggest one I see from beginners is that they underestimate how much work and long term dedication actually goes into making a comic, even a short one. Like it's one thing to hear, "This is really hard!", but experiencing it is another matter entirely. Even that standard page a week can be immensely stressful in the beginning, doubly so if you're not organized, good at time management, or comfortable in your art enough to bust it out without inspiration.
I also completely agree with @kuromonoart on the research bit. There's so much knowledge you have to accrue for good storytelling that people don't even think about. It's easy to tell when a creator doesn't have that foundational basis in reality, even in fantasy.
@revisionstudios yep, even if it's not real it still need some LOGIC! Nobody would read stuff that is beyond their understanding or unable to explain 
I second this!!
I don't draw, but letter my comics, and oh me oh my. I knew about bubble positioning and stuff, but never really paid attention to how people position the words inside a bubble before actually having to do it!! It's one of those ''got to feel it in your skin'' stuff.
I also think, as a beginner, I underestimated how difficult it is to pace your scenes in the space you stablish yourself. I like to work in definite spaces, so there's almost always this lack or excess of space and you got to crack your head open to make it work, to fit all in. It's a pretty nice kind of puzzle, though!
There is no relacement for hard work and experimentation. In a world built on trends of productivity hacks, self-help tools, and missions about "figuring yourself out", the one thing I had to resolve to is that if I'm going to make something Im proud of that others enjoy it's going to start with working hard, making lots of mistakes, spending lots of time creating ideas (good and bad), and learning little by little each day.
Sometimes you can't work smart. You just have to work hard until the right foundation is there. The best thing about that is later on you are grateful for those opportunities because you learn just how many obstacles you can overcome.
Your comic won't be perfect.
Expect lots of bumps and knots while working out the kinks in both your art and your writing.
Six Chapters of LoaA taught me this much.
Also, Make. A. Damn. Buffer!
That's the other thing beginners tend to overlook.
Being consistent will get you far even when real life gets in the way no matter what skill level you are at.
I, Myself, am a first grade beginner but during this short amount of time posting and publishing my novel, Youria The Third3 I realized that one must not shy away from editing and rewriting portions of your story. It via these constant modifications that one learns how to better improve their projects.
in my very first comic, I made it manga style when I knew very well it would make it less readable/desirable... I never changed it XD
Unless you can explain that it is impossible to explain, a.k.a Deus Ex Machina. It isn't easy to do that though.
What the hell is "the elder scrolls" anyway?! I'm look at you, Bethesda!
For all the beginners that may be looking this for learning:
good job, that was a smart move.
If your story has a continuity, have a plan about where the story is going, but don`t overplan.
don`t underestimate storytelling and dont underestimate art. At least one of these must be above average and the other must be at least decent.
Learn about panelling.
I'd say never start until you have a complete finished design of your main character. I felt so stupid making a comic about college students and I didn't even bother to design book bags for any of the characters.
The same thing goes for backgrounds of frequent locations.
hyperfocusing on their comic.
remember to eat.
do your homework.
work on other projects for variety's sake.
do. not. stress!
if you find that making your comic has become overwhelming, take a break. do something else. you can always come back to it!! 
That Comic Sans is the crappiest of all fonts to use for a comic- but yet I still see beginning comic artists using that font- especially when there are so many posts that suggest using sites like Blambot where there are appropriate comic fonts one can use for FREE.
I think you meant "learn the basic first instead of trying to do any art style".
Because any art style is needed to be develop from the basic. Having a good art style is not for beginner to be honest. You can only expressing your own style after developed your basic perspective and anatomy.
There's nothing wrong with doing the generic anime style as a beginner, you need to kickstarted your talent from somewhere, you know. You started it, you felt that's not good enough, then you will know that you need to learn and practice to be good. That's how I used to be.
-I'd say start with a couple small scale projects. It doesn't have to be long to be good.
-Learn from your mistakes. The more you finished a project the more experience you get (hence why it's important to start with smaller project).
See this as when you start drawing, is it better to start right off the bat with one unique hyperrealistic portrait that will take weeks to make it decent (with no knowledge of anything) or with 100 quick and rough drawing of heads that you can learn from each head you draw ? You'll improve a lot by drawing 100 heads instead of 1.
-Remember that it is okay to fail, don't pressure yourself for no reason, life already does that xD
-Don't start a projet if you feel like you are not ready, skill (art and storytelling) and mentaly-wise.
-Do not treasure what you create. If you prize your creation too much, you won't be able to reflect on what is wrong, how you can improve etc. Don't expect your project to be your magnum opus.
-And probably the most important tips, I received is : "Not all advices are good advices". What works with one person may not work with you.
Know who you can put your trust on but also know when to stand your ground and revaluate the "Rule".