"As far as leading the target goes - its a matter of practicing. Cant really give much help here. Play Secret Ops before you play Standoff - its easier. Also maybe it would be a good idea to start training with ships that have an ITTS system (simulator), so you see where you are supposed to aim (the green diamond)" -- cff
That's good advice cff. The only thing I can add to that is pretty much what I've already mentioned. Just experiment in the sim on slow moving targets first, even if they're friendlies, and with each gun and practice with each ship to get a feel of how their speed changes the velocity of gunshots. For example, one of the hardest ships to nail is the Gladius, as its laser projectile speed is significantly lower than say a Rapier. If you can master the Gladius, you're doing very well.
The most important thing is to know gun ranges like the back of your hand and to always try to go in for close range shots. Even if you miss a few during close quarters, it is far better than wasting a volley at an out-of-range target then having a servere energy drain just as the enemy closes in.
When you aren't confident with your marksmenship at long range, which I'll admit, I myself am not as good as I want to be, it is a good idea to lead an enemy that is moving at a straigt angle (for instance, when they are conducting an attack run on one of your buddies). Switching to the longest ranged or most energy economical gun is a preference some people follow. It helps generally, although it depends on the situation.
Also, short bursts of afterburners and rolls help focus gunfire in a tight arc around a target making it harder for them to dodge within a certain radius of their evaisive options. Sorry if this sounds confusing - it's hard for me to find the right way to explain. You can't tell a painter how to paint step by step, they eventually do it themselves once they get the feel for it eh?