Just some basic tips and tricks for flawless interaction on DeviantArt
Watch people when you honestly find them interesting.
Watch your friends, even if they don't have amazing art. It helps you stay updated with their progress.
Watch groups. They'll offer you a fine selection of art you're interested in, and will help you discover new (interesting) artists.
Check the faves of people you watch. As you like their work, you might have similar tastes in art. Checking their faves might help you find cool art.
Recommend art from people that you watch for a Daily Deviation (if good art, of course).
Uncheck all boxes when watching. There's nothing more disappointing than an empty watch.
Just watch people for points. It's lame.
Watch people for a watch-back. Many people don't do those. You'll only end up disappointed.
Commenting on profilesDo
Thank people for watching/faving you. It's not obliged, but it helps you to meet new people and stay in touch with your fans.
Comment on the page of someone you watch. People love to hear what you like about their work.
Post a few kind words on the page of a random stranger whose work you like. You might make a new friend.
Comment either in English or the user's native language (if he displays his location). There's a big chance he doesn't know other languages.
Ask people to watch you. It's annoying. Many people don't do this anyway.
Spam people with your contest/group/facebook page or whatever. If you have something to promote, do it in your signature.
Send messages that include "send this to a x-number of your friends". It's annoying.
Commenting on artworkDo
Read the description underneath the artwork. So you can understand what the artist meant with this work
Encourage the artist
Tell them what you like about the artwork
Balance your critiques. Even if you don't like a work, make sure to highlight the positive aspects as well as the negative ones.
Shut up if you haven't got anything nice to say.
Tell people "this reminds me of character-X from show-Y". It comes across as if the artist stole the idea from a certain show. Not very nice.
Tell people "this looks like character-X" and insist on it. Character designs have only so much variation. It's possible that characters with similar haircolor/haircuts look alike. That doesn't mean the artist stole the idea.
Tell people "you've copied this from artist-X". It's an accusation. It's impolite. Especially when you have no solid proof (as in; the original work or an exact photoshop overlay)
Post a comment that's all negative. It feels like you attack the artist.
Send a private message if your message is either too long or too personal to post on someone's profile
Randomly spam strangers with your artwork/group/whatever via private message. It's spam and it's annoying
Gossip about other people
Post encouraging words towards fellow artists
Share art tutorials / art books / art related websites
Feature work you like
Feature work from friends that need more exposure
Post things that are too personal. DeviantArt is an open website. Everyone can read your journals, including your boss or your parents.
Complain about another DeviantArt user. Other people have nothing to do with your problems.
Be too strong in your opinions. Stating you 'hate' a certain fandom is never a wise idea, unless you want angry mobs harassing your comment section.
Be a chronic complainer. People hate them.
Ask questions. Be elaborate. The better you describe the problem, the better the answers will be.
Use the search function to check if there's already a topic about your problem/question.
Complain outside the complaints-forum. People will mock you.
Post links in the thumbshare forum. It's for THUMBNAILS. Not for links.
Spam your work everywhere. There's a thumbshare forum where you can show your work.
Feed the trolls. Some people's only purpose is to get other people angry. Don't let them get you.
Add a description. People want to know what it's about.
Add the material used/time spend in the descriptions. This will prevent people from asking.
Credit the people whose stock material you used (stock rules differ per person. Make sure to read the stock artist's policy)
Submit your works to groups. It'll lead to more exposure.
If you make art for someone, tag this person. By doing so this person will automatically receive your artwork in his inbox.
Add a mature content tag if it includes strong violence or nudity
Post every random doodle. Quality over quantity will make your watchers stay.
Make hate art. If you hate a person/fandom, just let it be.
Replying to peopleDo
Reply if someone took the effort to write you a message (unless it's a simple "Thank you" -- those are impossible to reply to)
Block people and report them to the staff if they're repeatedly mean to you. It's better than fighting back.
Gossip about other people. People will be notified when you tag them. They will read it. Public comments will be spread fast. There's nothing as fast as the internet.
Be an ass