That's a broad question to ask... It depends on how many fish you want to keep, how much maintenance you want to (have to) do on your tank. If you want to keep corals or fish only. It depends on how much money you want to spend... I really don't know where to start. If you do not know much about keeping saltwater fish, then that would be the place to start. There are many threads, stickies and books which will teach you the basics. You need to know about the nitrogen cycle. What types of fish are compatible with each other. Proper acclimation and quaranteen techniques and more. Simply asking what I should buy doesn't really tell us much.