[Myka]

Bah! I just typed out a big long answer for you, and my internet connection crapped out. Grr.

Anyway, the short of it was that I like to buy kits individually because I find the packages usually have one or two I don't want, and are missing some I do want! I like to use high quality kits like Salifert or Elos for everything, but mainly calcium, alkalinity, magnesium, and nitrate. I don't mind using API kits for ammonia and nitrite which are cheaper because you really only use these kits in the beginning of the tank setup, and then only later on if you are having some troubles. I don't test for pH (check out the link in my signature for explanation). If you choose to test for phosphate (good idea), use a quality kit for that too.