in coops its going to be hard as there are long icons and the defenders know where you are from the brief.
so be sneaky
either 1) go as fast and as low as you can and try to hit it before they arrive or
2) wait. go a long way round and hopefully the defenders will be busy when you arrive. fly past a grid to the side and check if its hot, if not then make your bomb run, if hot go around and come back in 2 mins
with il2 you have to stay low as they are too slow.
With others its a good idea to get high. I typically ingress at 6000m, drop to 3000m a grid out, fly past and then turn and drop while heading home.
Only make ONE pass as otherwise you will get caught
hope this helps