Scams come in many ways, and I have experienced some of them. 
I will in a short while write about them, and how to avoid them. 
But in general, the biggest scams are;

Brokers that have an high difference between sell and buy (or takes your stop)
I will develop this later on when I have some more time.
 System "wizards" that want to sell you a system for just 2000 dollar... You can ask yourself, if they make so much from the system, how come they need to sell it ? ;-)

I will write more about this later on, hopefully in February or March.