Go to some highschoolers or college kids (college is more likely). Use some intelligence and you'll see which ones "know a guy". Most likely they know a pot guy. Most likely that pot guy either sells LSD or knows another guy. I wouldn't go too much further than that unless you're looking for meth. It isn't hard. I've never bought drugs and I guarantee I could have weed by the end of tomorrow because I know a guy who knows a guy who sells.