As of today, what's a good mixing service for BTC? I buy my coins from coinbase and once in awhile i sell them to my friends that doesn't want to deal with setting up on coinbase. Just to be safe, I don't know what they buy and don't care. But I heard reports that coinbase monitors where your coins go so I don't want to get in trouble if someone decides to buy stuff on the dark market.

Whats the best course of action? Mix my coins? or something else?