Now everyone knows that Trading with other races can give you some extra credits, also get some from marketing buildings that gives some extra economic boost based on your population levels. Most players hate this becuz gotta watch out for Morale otherwise it will get worst by adding too many farms and crap load of marketings is kinda stupid.

Now the big issues that most players dont realise that is also come from Manufacturing too. Let say you build three factories with no bonus on tiles, so if you wasnt building anything at the moment (no upgrade) you will earn extra credits for Manufacturing Points: 1MP = 1BC.

So get some minor planets for backup so you can build something fast like an extremely huge project or making one constructor every weeks.

I didnt care for other races, so there is no need for me to get involved with United Planets. This the only ways to get myself alotta credits and dont forget to build crap load of Economic Starbases it would give you economic bonus, but only Production and Research only. So watchout for Researching on any planets becuz it will eats your credits like mad (1TP = 1BC).

Good luck, enjoy.