Hey
@fire fist,
Before you begin building trust, it's important to stay safe while conducting business on sythe and also know how to send proper PMs. I'd begin by reading these two threads:
Trading 101 - Vouches, donor status and how you can stay safe!
Discord PM Template
As for building trust itself, there's a number of things you can do:
1.) Get involved with the community, put yourself out there so people recognise you. Get involved with community general, discussions, suggestions, welcoming new users, join the sythe discord here:
Official Sythe Discord
2.) Become a donor(which I see you have done)
3.) Make a vouch page where you collect vouches for services you do, you might want to offer some free services to build up some reputation (questing, skilling, etc)