This forum is the best for promoting to people who know what they are talking about.

Telegram is the best tool you have though, especially if your devs take the time to answer questions. The way an ICO handles its telegram is a really good barometer for me. Electroneum and Dragonchain are both really good at answering any questions people have.

There were a couple others that I opted out of because they just banned anyone who asked any real questions and it just felt real sketchy.