Is there anything I can do to prove to a potential seller that I am trustworthy?
Yes you can, use escrow service.
I am using my own personal verified PayPal account. I can send as F&F, and even write a note that I will never charge back if that helps.
I will of course go first.
This can add a layer however I do not think this will help for the dispute.
As an extra layer of protection, I can provide you with my own personal Facebook account having more than 1100 friends and videos and pictures of me from my local martial arts club. I have my whole family on Facebook, and a lot of people posting on my wall. It would be impossible to fake such an account. Will even send a picture with your name so you can see I'm the guy on my Facebook.
Don't do that. Keep your privacy here. Look around here and you will see everyone are encouraged to keep their privacy.
I don't know if this will help, but I really want to prove that I am legit.
Trustworthy? It takes time. For the time being you can use any exchange. Build a decent friend circle here. stay active, be a community guy. People will find you trustworthy.