Salem

Any Tips how to get it up to 6000? I stuck at 2300, only way I see is to build the Iron Stuff but this is realy expensive =/ because I only get ~ 30 Iron / day

Stuck? You know about curio grinding do you not? Using variety curios of any sort to reset your learning to 70% so you can use another Cloak and Dagger curio. Iron might seem expensive, but it's really cheap considering the mass amount of C/D it gives.

Other options are Wicked Wickerman, The Last Wishbone, Singing Old Log, Tumbleweed and Concordat of Worms. But you'll need variety curios for sure.

Hunting trophies aren't that metal intensive, they give decent C&D and provide some much needed variety.