Why not get a darkcoin wallet then use shapeshift.io to turn your bitcoins to darkcoins and then back to bitcoin, they will be completely mixed and no one can track them back to you.
There is no darkcoin anymore, also all this will cost you a decent % of your coins in fees.
Deposit and withdraw on BTC-e (or another exchange where you can create accounts/deposit/withdraw anonmyously) with an account made over Tor should do the trick.
darkcoin was just for example, there are I think 26 currencies listed there, you can even use litecoin or dogecoin and the conversion + Tx Fee would be the only % of your coins you would loose but if you're aiming for true anonymity than you'd have to pay a fee.