The book "The book on investing in real estate with no and low money down" has a chapter on wholesaling. Also, there is a free guide to it on the BP education tab. As well, it is very easy to find multiple different resources throughout the internet. Primarily, there is assignments and double closings (double escrows.)
Essentially, assignments are where you put a property under contract, then sell said contract to someone else for a fee. This can be illegal in some states due to brokering laws (i.e: what a state defines as brokering.) If you are a RE agent, then you can assign contracts without worry.
However, double escrows are safer in the fact that you buy the property, then immediately sell it, usually within the same day. So the house goes from A to B at 1pm, and from B to C at 2 pm. This method requires closing costs and other costs not incurred from assignments. This is important to note because after doing 30-60 deals a year, little costs snowball into large ones and detract from overall yearly profit.
Full disclosure, I am a moderate newbie and have gathered all this info from the forums, BP free weekly webinars (found under BP education tab I think), and talking to others.
Happy hunting!
