Always go to a hairdresser! Home highlighting kits are evil! :) Seriously, unless you have a friend who is a hairdresser, don't even consider doing it at home.

You could always try a college/trainee hairdresser if you want to do it on a budget as a first try. Upkeep can be expensive, having your roots done around every six weeks, depending on how quick your hair grows and how dark you are to start with.

Whatever you do, don't try to do it at home!