Before I start typing what little I know - I'm only occasionally dabbling in it and let wiser people in my group tell me what to do - I'll
link you to one of the experts on the BGS.
There's one more thing that isn't directly mentioned on the first page of that thread: UA bombing. You'll run into it sooner or later, so I might as well tell you how it works.
The arrival of the aliens (now confirmed as Thargoids) was preceded by two, at a first glance unconnected, appearances:
Unknown Artefacts (UA for short) and
Barnacles.
UAs can be collected with a cargo scoop (like any other kind of flying debris), but if you have them on board of your ship, you'll notice that your ship will get damaged. The ship's computer will recognize it as "corrosive cargo". Try to hold on to one for some time, and you'll find e.g. your cargo hatch deteriorating to a point where it won't stay shut any more, and the UA will drop out again. They have a similar effect on a station. Drop enough UAs on a station (i.e. sell them on the Black Market - no station will buy them willingly), and some or all station services will shut down. The only known cure at this time is to supply the station with Meta-Alloys, which you can harvest from ripe Barnacles. The vaccination would be to push the system/station into a state where the Black Market is shut down (supposedly possible - I have no idea how, but maybe you can find a few hints in the "
liberate rares" thread).