I have to share something I learned yesterday in mumble from Harkonis and Cortilian that was huge for me. I had trouble where every USS I would go into would be empty and I had no idea what I was doing wrong. At first I figured there were just a lot of empty ones, but the other guys told me almost all of them should have something in them.
Turns out I was trying to drop out of supercruise as close to the USS as possible, like <5km and many times this meant that the USS would swing around out of my view by the time I jumped out of supercruise. Turns out you have to actually be facing the USS and can even do it once you are at the safe exit speed and even multiple hundreds of km away! This was huge for me and has saved a ton of time and frustration.
Another trick is you can just go to supercruise and set your speed at minimum and just wait for a USS to spawn, then point at it, select it, and immediately exit supercruise into it with no waiting (many times they will spawn in your view, but check the navigation pane every so often to see if it is close, but just not in view). Awesome! I was wondering how some of you were farming USS so quickly and now I know what I was doing wrong. Hopefully this helps someone else.