I have a 1st-level sorcerer in my game that has a rabbit familiar. Familiars are magical beasts, so you can't use "speak with animals" or anything that specifically affects animals. As a result, she can't actually communicate with her familiar at all.
Other than to be an intelligent (INT 6) creature, the familiar seems to largely just be a liability since it's not like she can give it instructions. It sits in her backpack with its head poking out all the time but otherwise doesn't do anything.
So... what's the point of having a familiar at 1st level anyway?
Admittedly, she could get it a pearl of speech (MIC p118; 600 gp; Item Level 3rd) to grant it the ability to speak and understand a specific language, but that's quite a ways off for a 1st-level character. It seems to me that the only immediately useful abilities of a 1st-level familiar are the passive skill benefits (Alertness, and the animal-specific benefit), the ability to make it slightly less of a liability by sharing spells with it, and the possibility of leaving it to guard something so it can empathically inform you when something scary is nearby. However, that last one is useless to an adventuring sorcerer that's going to regularly be more than a mile away.