I always respond to my comments, even if just with a simple "thanks". Sometimes check out their comics too
I reply if I can think of something to say, but I don't over think it. I answer any questions. I don't have many followers to Outside the Box6, and it's usually the same people commenting on each page, so I've talked to most of the regulars at some point in the comments section. If someone takes the time to write a longer comment, they'll usually say something interesting enough for me to reply to!
If a creator follows me, then I check out their Tapastic page, sure, but I don't critique their comics without being asked.
Also, I'm not really sure 'fan' is the right word to describe my readers? There isn't any Outside the Box discussion outside the comments section (that I'm aware of??)
Pretty much what @hierogriff said. 
Except I admit I don't check out every new reader's profile. But for those who comment, chances are THAT will get me ninja-sneaking around their profiles...
I personally appreciate constructive critiques, but I know not everyone is ready for them 24/7. It's better to not give critiques unless asked.
I always respond to my fans, and I check out their comics if they have any.
Interacting with your fans is important, after all.
Yes to all questions.
I respond to every comment (good or bad). I don't take bad comments personally and most of the time we end up having a bit of fun by the end of the conversation. Critiques are welcomed. I'm extremely thankfully when someone takes the time to give a bit of constructive feedback to help improve my series. Good comments are awesome and keep me motivated, and silly comments are gold! I love having fun, and silly comments start the best conversations.
I visit each new subscriber's profile. While I'm there, I lurk a bit and check out their comic series (if they have one), Reading List, bio, and profile wall. Then I give them a "Thank You" post and try to type a special thank you for each reader, if I can. Sometimes I'll offer more comic suggestions based on their likes in their reading list, or comment on something silly in their bio, like "Bacon bits is the fairy dust of the food community." (there's no way I can past up the opportunity to comment on that) 
I don't give critiques unless specifically asked for it. I feel it'd be a bit rude of me, otherwise. However, I comment with jokes and what I like about a page on other comic series, and always try to say something supportive and uplifting to those that need it.
I respond to every comment (if the conversation allows) and thank every new subscriber with a "Thank You card."
I respond to 90% of my comments, I'd say. I like to start conversations with my readers, and get to know how they interpret the story. It's been really interesting, and my readers have even influenced a couple of minor things in the story, because of questions they were asking or how they saw a certain scene that was different from how I intended. I think it's made a better product in the end.
I'm going to start thanking my subscribers with a little "Thank you" card too.
I don't really use the word "fans" as it implies "fanatics" and I think the readers of my comic are not nearly that. They're my peeps, my readers if you will!
I will respond to any question or comment that needs answering, but... I'll delete negative comments or sexualizing comments on my work. Not because I'm a sissy, but if the negative comment cannot be followed with a reason for the negativity, it should not have been commented. Like saying "Why did you kill x character they were my favourite I hate you" is not a reason in the slightest, or unwelcome criticism I cannot build on. And I'm not quite in the mood to get into fights or tell someone off here on this website, where there's oo many great people. I'd rather jst sort them out else where or delete them entirely.
Haha I wish that people comment and talk to me more in regards to my comic ;u;
But anyways, when I do get a comment, or a chance to talk with readers I try to be as warm and inclusive as possible.
"There's no glorification in being busy."
I find there are too any comic artists these days that either think or use the excuse of "they're too busy" to at least thank their readers when they leave comments on their walls (this happens a lot with creators who are a lot higher on the popularity scale). It's fine if you don't have the time to have a long conversation through PM/public wall, but at least acknowledge them when they thank you for doing what you're doing and such rather than just leaving them hanging.
But it's still best to try and converse with them too, when you can :3 It's nice to learn about your readers and you can make some pretty awesome friends that way too ~
I try to reply to all my comments, but sometimes I oversee one or two. And I always check out the comics of my followers.
I have under 30 subscribers so that isn't that hard. I came to Tapastic for feedback, and I always take it in consideration and I learned a lot from it.
I reply when I have something to say, otherwise I usually upvote comments. I find that not all comments require a reply but I truly appreciate all the feedback I get. I love my readers. I gotta admit I don't often check people's profiles but sometimes I do!
I check out their profile and leave a comment for subscribers. I also try to reply to all the comments. I'd appreciate it if the artists that I follow replied to mine, so I try to make it a point to reply to anyone who tries to engage. That's not saying much, considering I only recently started uploading my comics and consequently have only a few (but precious) subscribers. I do hope to continue replying to as much comments as I can in the future, though.
It's also a good way to make friends and get closer to the people who support your work. I find it to be gratifying if they're happy with the interaction.
Communication without feedback it is not communication, so I always say thank you and look if my new subscriber has a comic that could possibly interest me, and well, I really like when I know that people is enjoying my story2.
I am not much of giving critiques because I know some people could be offended or they didn't ask for it right away :/ but I myself like receiving critiques....I have improved thanks to that.
If someone asks me for honest feedback I'll eagerly give it, otherwise it is improbable I do it
I try to respond to every comment on my comics. The only exception is sometimes the same person will leave several comments in quick succession, in which case I reply to those I feel I can say something useful to, rather than just repeating myself.
I take a look at the comics my subscribers make. Some of them I subscribe back and interact with, others I don't. It's just a matter of my personal taste. I rarely enjoy gag comics, for example, and I don't have anything particularly constructive to say about them. I wouldn't give critique unless it was asked for, or unless I thought there was something fundamental and simple to fix that was hurting an otherwise great comic (like badly compressed images).
I respond as quickly as I can to everything(if I "leave it for later" I will forget to do it), probably smothering them so they don't dare come back - yikes 
13 days later
I try to always reply. If someone takes time out of their day to read my work and comment, I can certainly make the time to give a response. If I were popular and getting an unwieldy number of comments I'd rethink it but for now, I do my best to interact. It's one of the great things about having a webcomic.
My followers on Tapastic are pretty easy to keep up with because I don't have many of them right now so I usually reply if I have something to say that is, especially questions, I always answer them in my best way without spoiling stuff xD My youtube and deviantart on the other hand are a bit hard to keep up with...
I like being silly and joking around and encourage readers to do the same. I love it when people have fun with my stories and try to cultivate a cozy atmosphere in the comments' section. And if we have a running joke I'll include it in future pages or if readers request some detail that can also be woven into the story. Interaction is the heart of webcomics after all and what makes them so much fun.