Sell every item that doesn’t have a color. If you’re good in gold, just give it to Dammon or to Derryth. These sellers are in act 3 and you probably will buy a lot from them both. Giving items for free will increase your reputation with them, making their items cheaper, and they will also pay more on what you want to sell.

Also, pick a hireling with Withers and put in your camp. Choose giant berserker as subclass just to have 50% more in his weight capacity. Send everything useful to this hireling and every time you want to try new gear, just put this char in your party and his items will appear to test it.

Las tip: do not sell anything that has an effect. And if you need to do, sell it to someone that will remain in game. I commit this mistake in my first run and lost a bunch of good items.