Surely a lot of it has to do with the time you've been doing it as well? It just takes time to source out the best / strongest gear, who's selling it and get yourself into a situation where you know that dealer, can pick up regularly and aren't going to be ripped off or sold something dodgy? The longer you go on, the risks are more reduced I reckon. In every way. Once you know what works for you and what doesn't, what's clean and what isn't, you're sorted. It's the initial trial and error of stuff that might land you in hospital after taking some dodgy shit.