There are a few things I do to help with aim.
1. Setting up your shots with crossing shots rather than direct 6 lead shots. It takes practice and merge techniques, but imo, is much more beneficial. If you are direct 6 shooting, it opens up a bigger chance of getting picked. It also means they can go left or right and down relative to cross infront of your sites using a crossing\snap shot and then checking 6 incase of pickers.
2. Set convergence out further. A low convergence means you have to lead further than a higher one. I normally use 400 for cannons and between 375-450 for 50 cals.
3. Use your rudder. I have peddles and hate the twisty, the rudder helps yaw your nose to get a shot faster, and helps you get your nose down faster if the try to nose down turn. This helps you get the crossing shot better rather than the lead shot. Rudder is extremely useful for getting a shot.
5. With 50s you need about 1 second of bullets in a stream and located generally in one area of the plane. The wing is generally the best place for 50s as all the bullets streamline and weigh it down causing it to rip off.
6. For cannons, again always good to streamline but it takes less and more of a lead, so crossing shots are much more important.
As with aiming any plane. Try to get your nose to where they will cross and then hold the trigger down for a second or 2. If you overshoot, turn off to the other direction or immediately do a strong virtical immelman up over the top for a spiral rope if you see they are going for the reversal.
All the best,
