Is there any way for newbies to build reputation besides spending months to become a regular? Maybe some kind of a guarantee given by an already reputable user?
Only few days registered in forum and you already want to take some shortcuts, that is usually not a good sign.
You can pay for copper membership if you want and that will remove some of the early restrictions with ability to fully post images.
Nobody can guarantee for anything in this forum, especially not with newbies who didn't perform a single trade, so you need to be active in forum if you want to built reputation.