As far as trusting your trading partners. You can check their feedback like most other trading sites. Some established traders may ask that you send first until you get your feet wet, but most of the time, trades send at the same time.
Welcome to the site. What do you collect? Sport? Player? etc?
I post videos on YouTube of my trades and my collection, busting packs, etc. Take a look and leave some feedback!
https://youtube.com/user/brodiescomics
https://leagueofcomicgeeks.com/profile/brodiescomics