First, you have to find a Chinese restaurant that does Dim Sum. Do you have a Chinese restaurant near you that is a huge room with a million round tables in it? Chances are if you show up on a weekend morning, you'll be eating Dim Sum. So, if you're just getting started, you can start with some basics: Steamed BBQ Pork Buns, Shrimp Dumplings and Chinese Broccoli. These will all be like foods you've had before just presented in a different way. Steamed BBQ pork buns are like a BBQ pork sandwich that doesn't drip all over you. Shrimp Dumplings are like chinese ravioli. And Chinese Broccoli looks a little different, but ends up being very similar, it just has a different kind of dipping sauce. After you've put down a good foundation with these, take a look at what's passing by on the carts and pick a few. Often there will be chow main or chow fun (try this one, a basic noodle dish with wide noodles) as well.
My last dim sum was pretty good. Some stuff I liked, some that I didn't take seconds, but everything was pretty good overall. Some things were particularly worthy of note:
Bun With Steamed Pork: You can think of this as a BBQ Pork Taco. This was really quite good. I'll definitely get this again next time I see it.
Chicken Feet in Black Bean Sauce: If you haven't had chicken feet, you should really give them a try. They're somewhat labor intensive for the food you get off of them, but when they're good, it's well worth it. These weren't close to the best I've had, but you gotta try, eh?
Deep Fried Pork Intestine with Scallion: If you're ok with the concept of a food, but worried about the flavor, deep frying it is definitely the way to go. This one was great. The flavor with the scallions and the sauce all came together very well. The key was to eat this while it was still hot. It definitely lost something as it cooled off.
There are some great deserts to be had as well. Some of my favorites are the little custard pies and particularly the sesame balls. Sesame balls are nothing to be afraid of. They're made out of rice, sesame, and sweet red bean, then they're deep fried. They're at their best when they are barely edible without permanent mouth damage from the hot oil. I get these every time I go to dim sum. You'll recognize them as the balls about 2-3" in diameter that look like they were rolled in sesame seeds. Don't be afraid to ask them for a fresh batch, not the ones that have been sitting on the cart. They'll only respect you more for it. Especially if you just finished off a plate of the pork intestine.
Happy dining! :)