Hey mate, I'm using FP markets. I have a leveraged account and a non leveraged account and I find the leveraged account lets me go short on more stocks.
I am only half way through my one and only short selling book and it is called Short Selling with the O'Neil Disciples and it is fantastic.
An example of a recent trade of mine below. Obviously not making bags here but i'm always looking to be at least 2 to 1 reward/risk.
Cheers