I know exactly what you describe when online as flying aimlessly, no usable compass, and never seeing anyone, until suddenly you get shot down. Unfortunately, this is the experience of many, if not most, players who log on and, understandably opt to fly alone for a bit in search of a dogfight and/or enemy bombers to engage. I include myself here - especially those times when I don't really want to get involved with other players and just want a few minutes on my own. The map is huge, the players few, and even the AI enemy bombers are limited in order to preserve everyone's frame rates. The chances of random encounters are not huge, coupled with the fact that it's f'king HARD to spot other aircraft -- be they friend or foe. Even bomber formations don't exactly pop out at you from a distance.
Drop your resolution. The sim is beautiful at 1920 x 1200, but the pixels are tiny -- hence so are distant aircraft. Running at lower res is painful, but you WILL spot aircraft much, much sooner. Beautiful = death; ugly = life.
Set FSAA in the game menu to OFF. It doesn't work worth a shyte anyway. At lower res you're already in Uglytown anyway.
Locating other aircraft:
Teamspeak. Teamspeak 3 to be exact. You probably know this already, anyway. However, you now have a dozen or more pairs of eyes working for you, just as you can contribute anything YOU spot. Reporting "low flak over Hawkiinge" or "one of our ships off Lympne just blew up" is valuable intel and pulls fellow pilots to that area like flies to...........uh......honey.
If you get on Teamspeak, try to pair up with someone, then fly a half mile apart side by side. It's far easier watching your wingmate's 6 from a near distance than your own. And if you DO get bounced, you merely turn in towards your wingmate and give the enemy something to worry about.
Build a window on your screen and customise it with "server" (for enemy aircraft sightings), and incoming and outgoing chat (for the same reason).
Doing the above "plugs you in" and affords you some mutual protection AND a chance at scoring some kills. Remember the scene from The Battle of Britain movie when the new Squadron Leader ((Michael Caine) had to tell the Keith Parks character that another of his pilots had gone missing? The lone pilot had gone up "for an instrument check" and probably never saw the 109 that nailed him. This frequently happens on the ATAG server, also.
Hopefully I'll see you up there and we can team up some time!