starbuck:
seconding stealthgrrl.
I shave every day, and the only requirement for laser is that you shave the morning of.
There are a few things to avoid for like a week or two prior, such as any lotions with Vitamin A deriviatives (Retin-A, Retinol, etc) since that makes skin very susceptible to sunburn. The laser exposure would probably result in a burn. Aside from those kinds of things (which any laser clinic should clue you in to) there's not much to it.
Post treatment:
Some redness/swelling is common, mine usually lasts for a few hours. Shaving the next day is tricky and can really inflame the skin. You may not have that problem though, depending on the darkness/patchiness of the hair you're trying to remove. Still, giving yourself a day or two to recuperate isn't a bad idea just in case you react badly to the laser (i.e. redness/swelling lasts a little longer).