Like the one guy said, start small. Mother Teresa said, ‘I do what I can, where I can, with what I have.’
For example: the dealer and her boyfriend next door. Start surveillance on them. Does he cook up while he’s there? Look for any patterns you can exploit, sleep, high, etc. If he gets high while there, keep track of his actions during that time. Does he just crash, or what? If their both high and passed out, slip on your ski mask and slip in quietly. Find some of her junk(which you would have identified during surveillance), and OD the fucker. Or both if you want. Leave no trace, don’t take anything. Wait a few days and report the odd smell(if no one else has by then). Police show up, find the bodies, H and cash, nothing appears to be stolen, just a simple OD, so no suspects.
Disclaimer: This post is for educational and/or recreational purposes only. This is not the voice of your dog Sam telling you to go kill all the druggies.