It's not really a guide and more like a tip, but here it is anyway
What most ppl do is disench their BoE items on their alts or main, but you can make a lot more profit if you're selling them on the AH. When I started my character (level 54 now) I had no gold at all and since then I started selling all my greens etc. Started with a price of 2g 99s 99c and buyout 3g 99s 99c and they started to sell even level 10 items and I have around 2k gold now on my first character. Also the 4 g buyout was for level 10-20 items you can sell level level 50 items for around 10g and blues for 30g.
Small tip: If you're around level 40 and low on money try doing ZF a few times and you'll get alot of Flask of Mojo wich you can sell for around 4g on my server. I never had a problem with money before and this is my first character I ever made.
twocents
Sorry for my bad english, just trying to contribute.