forget about bitcoin to buy drugs, go for pot 
being serious, there are better options now. no need to mix coins, just go for some anon coin like xmr/shadow/nav
I think no need to use altcoin, it will use a little effort and a little difficult, because even if you're using bitcoin to transact it does not matter because your identity will remain a secret, because bitcoin is very anonymousbeing serious, there are better options now. no need to mix coins, just go for some anon coin like xmr/shadow/nav