You will end up emptying your wallet when you first start play as you see everyone's shiny guns.
While having good equipment will have an impact to your game, I always found teamwork and attacking always brought the biggest improvements to my game.
I brought a friend along to a Holmbush (great site) and he borrowed a friends SP-1 (not a high end gun) and he killed it. Sure he was short and fast, but the point is tactics and balls go far.