How do we deal with druggies?
Get somewhere where you can cut up your wares, and more importantly, somewhere to stash them [preferably not in your own house], get some scales, some resealable plastic bags, a couple of mobile phones.
Don't let anyone owe you money, and if they do, try not to write it down in a book, as this can be used as evidence should you be prosecuted.
Don't waste your time selling lots of small amounts, as this attracts a lot of attention whilst netting you comparatively low profits, and don't deal to children.
:-D