This is newbie talk, so don't kill me. I want to learn, but it seems so complicated.
I want to - sell BTC for ETH, and then sell that ETH for more BTC than I started the trade with. Sounds like a simple way to start, yet I know it won't be.
My biggest concern is that there are so many exchanges. How the heck do I know which ones will pay me after I make an exchange? I know I have to check their reserve balance, but what else should I look for?
There are many exchanges which are legit and which actually pays you, whenever you do an exchange of assets or coins.
All depends on your requirements.
If you want to go for centralized exchange, then go for Binance or coinbase.
Now if you want to exchange P2P without and KYC, then you can try localcryptos.com .
And yes you need to understand that most of the centralized exchanges requires KYC , so if you are comfortable with that then go for Binance.
All the above mentioned sites/exchanges are used by me and till now they haven't gave me any single problem. Rest is up to you mate which you gonna choose.
Wish you good luck for your long awaited trading journey OP.