Fill out your left side first with myth/allegan, then you can worry about your accessories, which should be last to be upgraded. Early in my coil days, I had DL/crafted leftside, vanya head+body, DL hands+belt, myth legs+feet, with relic+1 and cleared up to T4 with no problems.

As for the other stats, mind usually triumphs any other stat, and any other secondary stat is up to you as it really doesn't matter whether you build for crit/det/ss. Peity is very useful though, by stacking that you will notice a huge difference in managing your mp. With 4200mp on T4 I was usually crying for ballad around p4, but with 4600mp I don't run out of mana.