This game was advertised as free to play. It seems that promethium has ended that promise. I have played this game for years. It is now time to move on.
Why are you spending diamonds? Crew selection? Don't have enough goods to repair ship? GE negotiation?
You get two choices of crew for free, one the default one and 2nd you can exchange the crew...now if you want more exchanges then you have to pay diamonds. Trick here is not to unlock many crew members, the more choices you have less chances of getting the crew member you want in the free pick...
For goods and Ge, nothing much to say...you need to build up goods...it is very easy with AF recurring quests. AS far as GE well you should have researched about that before moving to AF.