I find it best not to mix my cruising life with my personal life (work, friends, family,neighbours). I have run into people I know from work and socially on the online sites as well as in sex clubs. Online, I ignore them and make sure to remove any tracks (if possible), so not to make them think they're being stalked. I let them make contact with me if they chose, but I never initiate it. In person if I see someone I know when cruising, once it's apparent you recognise each other, I give a little nod and smile just to put them at ease. Sometimes, they chat, sometimes they don't. I leave the decision up to them. I am especially careful with work colleagues, and I stay clear as much as possible. That's my livelihood, and why potentially compromise it any capacity?
Basically my philosophy on this is "Don't shit on your own doorstep", and it's served me well over the years.