How can I get noticed on this site?

There are various ways to get noticed, but the main one is comment comment comment. Post replies and threads in the forums. Comment on peoples artwork and user pages, use the chat room and the shout box. Give out good and constructive comments, to stand out - many people will like to return the favour. leodadominico has written an elaborate journal entry about how to give good comments here. You could also join one of the many clubs which adopt new people and help them to get exposed.

Also, try to remember that deviantART is a community, not a comment machine. You don't get anything out of it if you don't put something into it. In other words, you reap what you sow.