The main differences are when you are trying to cut the stuff. You need sharp scissors to cut kevlar and sanding both materials is a bit of a nightmare. Kevlar fluffs up and carbon produces nasty fibres.
In terms of layup you can treat them almost identically to glassfibre but you should try even harder to get a good layup to make the most of the extra material costs. Using peel ply is relatively cheap and easy and would help with getting good consolidation, save resin and gives a nice surface finish. Vacuum bagging would help even more if you can be bothered.
One tip Ive learnt with using Kevlar, if youre not after ultimate strength or stiffness and just want the part to hold together after sustaining some damage, layup the kevlar in the middle of the ply stack but make sure it stays relatively dry. That way the fibres wont break after an impact and will loosely hold it all together.

This tutorial seems pretty good for general composites work:
http://rv8a.tripod.com/fiberglass.htmlhttp://rv8a.tripod.com/fiberglass.html
& for the higher tech stuff:
http://www.netcomposites.com/education.asp?sequence=81http://www.netcomposites.com/education.asp?sequence=81
good luck!