There are many approaches to recruiting volunteers. One is to headhunt the people you like, another is to create great volunteering opportunities, alternatively you might like to have a clear get more involved sign in your community.
Here is an even simpler tactic. Decide upon something you want to do in the community. This might be hosting an event or webinar, creating a new content series, launching a new group, embarking upon a new cause etc..
Now ask who wants to be more involved. Use a forum post to do this. Let peopel put themselves forward to help. Most people want to be part of something.
There is some psychology here. Once an individual has stated once they’re happy to help out the community, they will begin to see themselves as someone that helps out the community. They want to be consistent with their previous actions.
So, for example, state that you will soon be launching a ‘beginners guide to {topic}’ and ask people to put themselves forward if they want to be more involved. If you can get someone to put themselves forward to volunteer once, you might have them forever.