It's not advertising. That's invasive and usually clogs activity.
The best way to monetize a community is to develop products/services that your audience really wants to buy.
You're best placed to do this.
You can identify the common problems that keep coming up. You should know the audience better than anyone. What would their dream products/services look like?
Do you know the best part? You can ask your members what their dream products/services look like and develop these for them.
The best tend to be educational courses, coaching, books and guides. But you can also do events, develop entirely new products/services (see The Travel Hacking Cartel), and exclusives.