I think Bitfinex and Bitmexbtc.co are pretty good sites to trade with MARGIN.

That means you can borrow funds to make the trade, and usually borrow more than 3x or 10x your account's btc balance.


I recently wrote a very easy to understand tutorial for how to trade on Bitfinex. It offers 3.3x leverage so still quite conservative. Read more about it here: https://bitcointalk.org/index.php?topic=1805736