sorry in advance if this is the wrong place to ask, i wasn’t sure.
I feel like in the last couple months i have really stepped up my quality, both in texturing and topology-wise.
so I’ve decided to start selling some models, and i’d love to hear tips and tricks from those already in the business.
what to do, what not to do, and how it looks so far. thank you 
https://www.artstation.com/gerardusnl0/store/PO57/pbr-pirate-assets-game-ready
Very cool man! I love it. I don’t sell models myself but here’s my 2 cents just from being a business owner and entrepreneur. Definitely the thumbnail is one of the most important. If you look at youtube videos or anything on social, the things with great thumbnails get more views. One of my videos got 500k views just because the thumbnail whereas others didn’t get as much. Your thumbnails look great! Maybe there is a couple things to tweak for them but I think they look good.
Second, if you are able to offer a small thing for free, that way people can download one or two of your free models and then they get used to your work and fall in love with it and then want to buy your other things. This is covered very well in the book “jab, jab, jab right hook” by Gary Vaynerchuck. Give, give, give then ask.
Other than that, just posting in forums and FB groups and getting your models out there 
Anytime man! Let me know how it goes 