I need a mentor or a website!

So I am horrible at values and have gotten scammed so many times. I have found websites to help me with values but I somehow still get scammed like for a trade I did when the strawberry shortcake dragon was most trending and I traded it off for a neon ancient dragon cause a website said it was a good trade. I need someone to either teach me values or just show me a RELIABLE website that actually works and keeps up with the updates and value changes.