With SOs now available at the lowest levels... the starting strategy is to skip TOs (which had a purpose back in the earliest days, literally training users on how to use enhancements) and DOs, and buy only selected SOs until you can afford full slotting. Opinions vary on when to start messing with IOs etc. but I think the consensus is that they aren't worth much before mid-30s... you're better off selling all salvage and recipes (oranges on the market) and saving up/buying SOs and the new Upgrade as needed.
Slot all damage for Acc first, no less than 1:1 with Dam: Acc, Acc Dam, Acc Acc Dam, and so forth. Acc=hits, which tops fewer hits with more Dam.
Don't slot more than three of anything anywhere. 3 SOs = 96%+ boost; a fourth gets you to ~104%.
There are very few builds that don't benefit from three slots in both Health and Stamina as soon as you can spare them.
Cue four pages of intricate IO, set, attuned etc. recommendations. 🙂