Ive found Salifert test kits to be the easiest to use and fairly accurate. I have used them all and keep going back to Salifert. If you're just starting off get the Mg, Alk,Ca, PO4 and NO3. These should give you a good idea of where you're at. Down the road if you want to keep more sensitive corals like Acros then look into the ultra low range hanna checker to keep a closer eye on PO4.