I have a whole character full of jewels and idk what's valuable and what's just reroll mats. Which ones should I be keeping ?

keep the good ones.

do you need a whole handwritten list?

look at people's iso lists, learn the affixes and suffixes.

18-20 max +

15 max with good mods
9 dex 15@res

those are some popular common ones.

the best mods are enhanced damage, max damage, resist all, dexterity, strength, and sometimes min dmg (mostly when coupled with max dmg on same jewel)