I'm no pro, but that's a tough one to answer. When I was starting out, I researched for about a year and read everything I could before spending a dime on hardware. My goal was to fully understand all of the component options and settle on what I thought was best - for the type of tank I wanted.. (in my case a FOWLR)
I'd grab a few books and check them out, it'll give you a nice understanding of whats out there. good luck