if you're rolling around 60% accurace on primary and secondary guns you're good to go. I beat the game on hard (fs1 and 2) and I think I was around that range on average, maybe slightly lower on the primary, maybe slighty higher on secondary.
In general, you're going to want to use your afterburners a LOT in combat, especially to close in on an enemy fighter/bomber to get a better shot. Yes, they'll try to run away from you, which is annoying, but you can either use the afterburner at the right times to keep pace, or do the little trick of turning away so they turn around to chase you, and then whip around and blow them up. Missiles are also wonderful.
The game will also get a bit easier once certain technologies are available... don't know how far you are so don't wanna spoil anything.

A good way to dispose of enemy fighters quickly with your primary guns is to use the brake trick:
Close in on the enemy fast by going full speed and using afterburner. When your close to him, open fire. What your enemy will probably do now is to use his afterburner and fly out of sight by trying to go around you. If you afterburn after him, you will most likely never get a shot at him.
But, because of his high speed your enemy will fly around you in a very big circle. Therefore, breaking to a full stop while turning your guns towards him, should put you in a perfect position to fire your primaries at him. At zero speed most FS crafts turn around so fast you can keep almost any enemy in your redicle for a long time. But still, only stay at zero speed for a small amount of time, because you will make yourself an easy target for other enemies not chased by you. Use afterburner to get up to full speed again quickly.