Mission 17 – Interrogate Charlie's Pushers
There four hostiles at the informant's house- a sentry out front, the informant inside, and two guys beating somebody up in the backyard. Approach from the east, and hop the fence into the back yard, behind the shed.
You can whistle apart the yokels, or just walk up to them and brutal takedown one to stun the other. Then it's a straight shot into the house to secure your first informant. You'll have the choice to recruit or kill (always recruit if possible- it's more money and power for your network in the long run), but either way the informant will end up lying on the floor, and you'll have a new mission objective- to take out Charlie's enforcers.
For style points, leave through the front door and take out the last sentry unawares. Consider it on-the-job-training for him (if you're using non-lethal takedowns, I guess).