Hi there Kalinn! Welcome to DPF! There are a TON of tips and tricks here, just look around in the pin discussion or help forum, or use the search bar to your advantage. (Or if you have any questions, just ask!)
As for general advice: If a deal seems too good to be true, it probably is. It's a sad fact that there is a large knockoff market for pins, which are generally called "scrappers". (These pins have either been denied from the parks due to quality, or have been duplicated without the okay of Disney.) You'll see on eBay these "lots" of pins which go for less than a dollar. Those are big red "NO" flags. If you see them, go far far away.
Other than that, my only advice is just have fun! Always remember that pin trading is just a hobby, and be kind to all you meet. If you have any questions, just post in the threads or if you'd like to PM me directly I'm cool with that as well! I hope you have a wonderful time here.
(P.S. LOOOOVE Your signature!)