1. All those excess blechs in your inventory that you don't use? Don't just sell them. Auction them!
5. Use drop armor and quest armor only. Don't bother actually buying a set. Sure, your level may get behind but it'll be worth it in the long run if you're wanting more gold. :]
Conflicting advice there. Although you may be telling one person to sell, but not buy, remember that SOMEBODY has to buy his stuff if he wants to make any money.
And really, nothing wrong with buying in the auction house. I would recommend doing that, considering you can get stuff just as good as what the Armor/Weapon NPC's sell, but at 30% of the price. Besides, the prices on most green items is very low anyway. What does sell can get you a bit of supplimental income, but unless you find something with 3-4 stats being desirable ones, you won't get much, if anything. Meaning...
Green stat heavy armor
+Int, +Wis; +Cast Speed, +M-Crit Damage = nobody wants that
+Str, +Agi; +P-Healing, +Attack Speed = something like 1-5 gold to a Knight, depending on equipment level
Anything blue or better sells higher, but also based a bit on how many stats are desirable. A heavy armor with Cleric attributes simply has very little value, even if it is blue.
Also, I wouldn't craft. It's expensive to do, might fail, and the value of crafted items isn't so high due to zero resell value thanks to being unsellable after equipping.