This is probably common knowledge (I didn't know), but don't sign anything until you are sure that the agent/company you have is the one you want. I made that mistake when buying my place, and ended up fighting with my agent up until we closed on a place.
When you sign the agreement, you are locked in for a determined amount of time to the agent, and even if you find a place without the help of the agent, they will still come collect their commission. Generally the time you are committed ranges from 6 months to a year.
Anyway, just make sure to check references. There are a lot of scumbags.