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?
If you don't want Coinbase to see where your coins go to then don't use them for first time sending. Withdraw all your BTC from Coinbase to your Bitcoin Core (or Electrum, Multibit, whichever you prefer).
After that you can use other exchanges to deposit and withdraw your coins. Once coins goes to another exchanges hot wallet Coinbase can't trace you.