A good tripod will outlive both of us, so it’s rare you’ll need to invest in more than one over the course of many years. A few extra bucks goes a long way towards getting having a more stable, secure setup.
See Really Right Stuff, Manfrotto, Gitzo, or Feisol for excellent tripods. In my opinion, you should strongly consider carbon fiber over aluminum; they are the lightest and strongest on the market.
#5 – Lenses
This is where the fun begins, and your wallet ends. Lenses are the single most important piece of equipment in photography. You can have the finest camera, tripod, backpack, media card, and accessories available, but if you don’t have quality glass, it will severely complicate your ability to take a good photograph.
I typically prefer to shoot with prime (fixed focal length) lenses, as opposed to using zoom lenses. My preference for primes is mostly about making sure that I get as personal and into the scene as possible.
With zoom lenses, I tend to get a bit lazy and shoot without adequately working the scene. There is no substitute for moving your feet and SEEING the composition with your own eyes, and not just through the viewfinder. The element of perspective is lost if you simply zoom, instead of walking around and checking things out with your own eyes first.
That said, it’s strictly a subjective thing. I know plenty of photographers who prefer using zoom lenses, and that’s great. Most of the time, the best gear for you is the gear you’re most comfortable with. The key suggestion here, with any lens, prime or zoom, is that you RENT one and try it out before buying it. You can’t know how the lens will work for you until you use it in various situations.