Pick delivery missions in titan's daughter, Taygeta system, deliver to Cavalieri in electra. Build your rep with the factions to pick the best missions.
EDIT: I'm being downvoted by a few players because I'm sharing a gold rush. Yes, FDev may nerf it. But the next gold rush is just around the corner, and another player will share it the same way I just did. The greatest thing of this game is this awesome community and the massive share of information. There are databases and sites maintained by players. This reddit. The forums. YouTube creators. The player who discovered Borann, the one that discovered Robigo, double painite hotspots, you get my point. All this helped me a lot in this game, and now I want to give it back.
Gold rushes come and go.
This community stays.
Let's help each other.
EDIT2: Seems like this gold rush is over.