Hello! I am new and have an answer! Friend is important to be an active reader and write more often. Comment, report and rating will grow the only thing that will not be fast. Do it every day.
Trust is usually not influenced by number of posts. The quickest way would be to just buy stuff from people in the services and goods section and hope that they will give you positive reviews.
You must be stating a fact. You have several positive trusts.
I just want to say do not blindly trust the numbers (20 0/+2 and similar). Sure he has a lot of feedback but not much of it is backed by serious reasons and note that most of nathams trust is from 2 users (monbux and EFS)
Myself did a trade with kilo17. I sent him 1+ BTC unescrowed and after that he sent the goods to me. That's what I see as well deserved trust (because he could say byebye to me after receiving the funds).
In other words: Always check also the reason for given trust.
Don't get me wrong, I'm not saying nahtnam is not trustworthy (I believe he is) it's just ... you know ( i hope you see what mean ).