Honestly it comes with experience. Believe it or not, my trading strategy keeps evolving and has changed quite a bit since I wrote this article. Here is my most recent post about selling by evaluating some level 2 data
https://steemit.com/trading/@oneluckyflip/oneluckyflip-s-crypto-trading-tips-and-tricks-placing-sell-order-on-a-low-volume-coin
Just keep trading and your success and mistakes will form you.
Also, 50% is GOOD so you are doing something right.