the major issue I have is AIMING!
Glad you like it. Aiming imo is best learnt by using the Bolt Action exclusively. You learn everything you need to know in the game the best by using the bolt - hip shots (how and when to), iron sighted shots (leading and making your 1 shot count), nade use and sneaky kills with the bayonet. Its hard to start with but IMO once you start feeling confident with the bolt action all the other guns are much easier to learn. If you start playing with the smg's and semi's then you don't really learn to aim so well and will just spam shots till the enemy dies, because 1) you can spam shots and will probably get some kills (but won't learn anything), and 2) because of the lack of accuracy even if you are aiming its not as obvious which shots were the good ones. You'll end up a much better player by using the bolt as much as possible imo.
Anyway some tips for aiming with a bolt:
As you probably know shots take time to hit the target so you shoot infront of the enemy. The faster he's moving and further away he is the more you have to aim infront, but its not very severe. Your ping might determine how much to shoot infront too.
For longer range shots were the enemy is probably not being too random you should lead your gun infront of him a bit to get your shot just where you want it and then shoot. Another way is to place the gun sights in his path and then shoot just before he goes into your sights. Both these ways minimise any fast mouse movements and makes it much easier. Its not like CS where you aim and click as fast as possible. You usually have plenty of time to take on your shots (at longer range). If hes not moving then just point and click the top of the sights on him. There is a little dip but its hardly noticable
When close range you don't really have time for iron sights usually - you will waste time (if its an smger or semi he will hip shoot you before you get the sights up). So ideally you don't want to fight up close, BUT you have to at least risk fighting up close to get in capture zones. So what I do is take regular hip shots even at people that I could safely iron sight - just for practice. Eventually you will at least have a 50/50 chance against smgers and semis at close range.
Always put on the bayonet (and only use the default bolts). Up close its V useful after taking your hip shot, but only really advisable against other bolters or people that haven't seen you yet, but even then you should just go to iron sights to shoot him if you can because he could hear you breathing. So either charge and hope he doesn't turn around (hold sprint and your melee button down and release just before you reach him) or go to iron sights. As a bolter you should have your melee button easilly reachable and prefably a mouse button (because you need to be able to manuevre a lot while holding the button down.)
Theres more but probably too long a post already for this part of the forum
Edit: forgot to say you need a high resolution to compete in RO imo - at least 1600 x 1200 - so you can see the little pixels at long range. If it means lowering the graphics quality its worth it imo. And turn HDR bloom off! It just makes everything harder to see.