Wow what a fantastic reception ☺
This morning I accepted a "black box retrieval" mission, was mildly confused scanning and using the FSS, was a bit more confused until I realised I'd "filtered out" signal sources, then like the Anti-Bono, found what I was looking for.
Not sure if I needed to FSS though.
See, this is an example of how ED doesn't really give you hints that you're missing something.
As a rule, it'll be the same procedure for
any mission that involves going to another system to find/scan/recover/explode something - as well as for other things, such as hunting for engineering mat's.
Jump into the system, target the system's nav buoy, travel to it, drop out of supercruise,
target the nav-buoy and wait until the scan is complete.
This will, basically, give you ALL the information about a system; planets, stations, surface bases, signal sources
and Points Of Interest (POIs) related to missions.
So, if you're doing a black-box mission, for example, you head to the target system, scan the nav-buoy there, jump back into supercruise, look at your nav-HUD (the one on the left side of your ship) and scroll down it until you see something that says "Mission Related Signal Source".
Target that, fly to it, drop out of SC and scoop your black boxes.
Also, while I'm at it, be aware that although most of the time collecting black boxes is straightforward,
sometimes you'll get attacked while you're doing it.
In that case, feel free to just grab one or two black boxes (or none) and jump back into SC.
Another mission related POI will appear and you'll have another chance to collect them.
Don't feel like you have to collect them all at the same time if you're being attacked.