I purchased equipment tenacity from the epic store with my first batch of earned (by playing) currency after maxing out all the “get MOAR/BETTAH quests” stuff. It’s freakin’ busted, as it allows you to wear equipment you couldn’t normally use, and more importantly you can level that equipment.
This lets your auto-rebirthing always low level characters still level gear, even though they normally couldn’t wear it. You also get a fraction of the bonus of the gear, and it seems pretty high (perhaps it’s calculated as the sum (character attribute requirements) / sum (item requirements)), so it can be 80%+ effective when you’re still missing a bunch of some stat that you will not see for another 50 levels.
The other recommendation I have is to rush a level of the global skill slot from the guild when you can. You get more damage (or a cool ability like my warrior borrowing a thief ability to teleport backstab people) AND you help the character who’s skill you are borrowing level up that skill.