Welcome, Julie. I'm pretty much a newbie, too.
Join groups - ones that fit your niche or a subject or that have the highest number of members or most activity - or some of each. Participate in those groups.
Pay attention to pricing - how it works.
Comment on images. If you comment on mine, I'm likely to look at yours! (just as an example - and Richard obviously has looked at yours) I believe comments are open to the public, so if you have a critique or question, ask it privately.
Have fun! Meet new people. Check out how many people you never heard of are on here from your home town/area! :-) That was an eye-opener for me!
Carol