I am somewhat new to playing in cash games as well. I've only experienced playing in them five times, and the first three times I was so nervous and I was still playing with a MTT mindset. I didn't do too poorly, but I took a break from it for awhile and gave it alot of thought. At first, I was thinking I'm not cut out for cash games, and am better skilled with tournaments, but then I decided to go for it again...After playing in two cash games over the course of the last two weeks, I've since done a 180. I am loving cash games now, and feel that I will be much more successful in the long run playing them rather than playing in low buy-in tournaments.
When you first start playing in cash games, whether you're successful or not, chalk it up to a learning experience. I'm not sure what style you're comfortable playing with, but I suggest playing extremely tight your first 3-5 games. I'm still adapting to cash games myself, but I've already recognized that at these levels, there will be calling stations at every corner, playing everything, so be very leery and open your mind up to all possibilities.
Good luck and let us know how it goes for you!
Edit: I like Poker Kid's tips! Specifically adjusting to pre-flop bets. Understand that the majority of the time, players will be betting 5-10+ times the BB. This is what I had not planned for when I first started playing in cash games, and it completely caught me off guard. A lot of players will bump it up with nothing, so wait for good
hands to call with and then let them bet into you. If they bet big, come over the top and push all-in if you're holding the nuts. I've been bluffed my entire chip stack several times, to try to get me off a hand with a relatively medium sized pot, and they seem to call every time I come over the top regardless of whatever they're holding.