I collected as a kid. It peaked my interest a little bit and I have been looking around to see what is out there nowadays. Man there is so much out there! The What Not app is a black hole of sports cards.

For those of you who collect here are a few questions:
1. What do you collect?
2. What app or other resources do you use to look at values/rarity, market pulse, etc...?
3. Do you sell some of your stuff and where do you sell it?
4. Any other tips for dipping your toes back in the hobby without getting burned?

TIA