First off, my ranger is lvl 24. I leveled that bit before the nerf, so take anything I say with a grain of salt.
There is a food that raises both Racc and Ratt.
Flounder Meuniere. It also gives you enmity -3, which is handy for a ranger. I used that while I was lvling.
Now to make Sidewinder or Slugshot More powerful, first you have to know how the damage is calculated. The short answer is all bow skills rely on your Str and your agi, all gun skills rely on your agility.
The damage Calculation for those skills inparticular looks like this at lvl 59.
Sidewinder
({Damage of your weapon} + {[your Str - Targets Vit] + 8}*2 + {[str*0.16]+[agi*.25]}*.91) (Acc TP modifier fits in here somewhere)* ([your att]-[targets def])
Slugshut
({Damage of your weapon} + {[your Str - Targets Vit] + 8}*2 + {[agi*.30]*.91}) (AccTP modifier fits in here somewhere)* ([your att]-[targets def])
With both of those skills, The more TP you have, the more Accurate it gets.
Also, you'll notice with bows, Str and Agi are modifiers, and with guns, it's just Agi.
The WS info all came from
here if ya wanna check it out yourself.