Ditto on making sure fermentation is complete before bottling. Just because the airlock activity has slowed down doesn't necessarily indicate complete fermentation. Take hydrometer readings, and if you get the same reading 3 days in a row, it should be ready to bottle.
Also...when you bottle, make sure the priming sugar solution is mixed well with the beer. If it isn't, the amount of sugar can vary widely from one bottle to the next. Give it a good (but gentle) stir in the bottling bucket, being careful not to splash or otherwise draw air into the beer.
Congrats on your brew! Let us know how it turns out.