Sharing is caring! Na Chem has a large station, easy repair, reload, and cash-in. There's a system nearby with interstellar factions so you can pay off any bounties you might incur while getting your reputation up.
I spent the last week there building up my reputation (mixture of assassination and planetary scan missions), and then stacking massacre missions once they came up for offer. I lost count of the credits I made, something around 2B I think. Was easily making 200M to 300M per stack of missions.
Lots of fun, lots of dakkadakka!
Sorry. didn't take any good screenshots.
Source: https://www.reddit.com/r/EliteDangerous/comments/u12dvs/good_massacre_mission_location_37_librae/