I’m not the best bomber ace, but sometimes I manage to be quite useful for my team. I try to give some hints, I hope some of them will help you!
I mostly fly the Il-2 in Moscow, but maybe these hints work for other planes too.
- Locating the enemy
In most cases searching around the cap point is worthy. If the enemy is attacking look for a building or group of trees, bushes about 30-50 meters from the cap area toward the enemy. Chances are good that there is an enemy rally point to launch their attacks.
Another hint is to spot tracer rounds: if there is visible heavy gunfire coming from a forest patch toward friendly positions there must be some enemies.
Target marks by friendlies can be misleading: maybe your comrade marked just on single sniper, and it’s not worth to waste your bomb load for a single kill. When I’m on the ground and I see multiple enemy soldiers I put three marks close to each other in the general area - signalling that there are multiple targets to hit for tanks and airforce.
I also frequently use the “ask / show enemy positions!” message from the chat wheel. I send this message when I on road to the target area, and about 2000m from it. (Usually when I turn back from the ammo-reload point.) It gives enough time for your team to mark targets, and marks placed this time won’t disappear until you get there! OK, it’s quite common that your mates too busy to mark targets for you but sometimes you get usefull targets.
Approaching your target
By default you fly head-to-head towards the enemy attack direction. Many of them uses covers. If you release your load from head-to-head position the covers could protect them from your attack.
So after an ammo-reload it’s not a bad idea to pass beside your target about a couple hundred meters, leave them behind about 1000-1500 meters then turn around and get them from behind!
This approach has many positives: you can kill whole squads “parked” behind a building while its player is forward in combat. Most tanks are headed for action so if you get around them you can attack their rear side, their engine compartment. Armor is much more vulnerable here than their front armor. You can kill Pz.IIs even with your 20mm cannon with some lucky aiming.
Honestly I don’t have the patience every time to go around them but its really worth to plan your entry direction rather than just fly straight toward the enemy.
I also use my guns too: start to strafe your target area from about 800mm. You can add some light rudder movement too to spray a larger area. You can get a lucky extra kill or two this way.
With the Il-2 I usually make two passes with one ammo load. At first I release the half of the rockets from couple hundred meters and when I’m very close to the target - but before I reach it! - I release half of the bombs too. At bomb release I go very low, almost scratching the roof-tops and trees. Go around and on the other pass you fire the rest of your ammo.
With some luck some enemy squads will spawn or arrive during the time your two passes. Or you spot a different target during your first low pass and you can attack that with your second strike!
With the Il-2 I usually fly at about 800m. Most enemies are flying lower than this, so you will get height advantage against them. When a Stuka or a Henschel biplane attacks you wait until it bleeds its speed trying to point its nose towards you from below. When he is slow you dive onto him with high speed. If you see a Bf 109 start to pray. 
That’s all, I hope it helps. Blue skies and good luck for you!