Start with a good rack and a set of rear panniers. Then add either an handlebar bag or a large saddle bag, depending on your preference. Get the front rack and panniers last.
For equipment, start with on the road repair tools and worry about camping gear later.
I'll put in a recommendation for the Jandd Expedition rear rack. A week into a four month tour last year, I crashed hard enough to destroy my front wheel and rip the hooks off of one of my rear panniers. The rack's rear support was slightly bent. I lashed the pannier onto the rack with cord and finished the tour without incident.