Hi and welcome! I was also nervous joining the site, but haven't had a negative experience so far. All the users I've met are pretty nice and genuine people. This is a relatively small community, so the ratings and reviews are taken pretty seriously. If anyone actually tried to scam you, you can submit a report and/or write a negative review.
That being said, if you want to be more careful for your initial trades, I would recommend finding people who already have at least a few reviews, starting with less valuable card trades, and you can also request each other to provide a tracking code for the mail, to make sure something actually got sent to you. If you are nervous about providing an address, you can look into getting a PO box.
While I can't provide much info on the payment aspect (I've only done trades not buying/selling), I know a lot of people use venmo/paypal. I'm not sure if the culture here is payment upfront or payment upon receiving the cards.
Other than that, you can just send people an offer or message, and negotiate a trade until it's accepted. I'd be happy to be one of your first trades as well 
Good luck and happy trading!
Hi! I'm new to this site, and a little nervous of being scammed since it's all around shipping and digital payment.
How can I safely go about a trade?