I know about contracts and the massive awards that they give when completed, but you can only complete a contract once a day. So, other than contracts, does anybody know the BEST way to earn credits?

I'm currently trying to redeem my credits for a Refined (224 at the moment) and I get to the trading part but It doesn't involve the credits? See, whenever I put something in the bots slot, in this case a Refined Metal, it then asks me to put one of my items in? So I do and I ready up and so I...

So I got myself 50 credits and I wanted to test StoreBot so I send him an offer for 1 scrap the offer gets declined but when I type !credits it says I have zero So I think it's broken... P.s. Loldielol don't you dare reply "did you break something again" :P