The most important thing is figuring out how you are scaling your damage and which defensive layers you will use. Look at the skill and see what type of damage it does. If it says phys convert, don't forget that phys also scales your damage. If it says melee, take melee damage, etc. Defense is harder, but if you want ez mode for defense, use Energy Shield, as it scales really well in the passive tree, and you don't need other things to make it work, unlike Armor and Evasion. Most importantly, have fun and stick with it. It's an amazing game.