Some would say that you don't need any test kits.
I use kits that test for PH, GH, KH, nitrates, and phosphates. After a tank has been set up for a while and I get a feel for the rate at which it uses nutrients, I test only once a month or so, and then mainly for nitrates.
I have an ammonia test kit but I have never used it.
Some test kits are good and some are not. Here's a link to an evaluation of phosphate test kits that I made three months ago.
http://www.aquaticplantcentral.com/f...test-kits.html
Good luck!
Bill