In addition to what Libertas said on tumbling/mixing your bitcoins, probably the most respected bitcoin mixer (I prefer the word mixer to tumbler as it more accurately describes the process) is BitcoinFog. Basically you create an account and can generate up to 5 receiving wallets, and then you can withdraw the coins for a 1-3% fee (randomly varies between those percentages) to up to 10 different addresses. I use it all the time. The link is below:http://fogcore5n3ov3tui.onion/