If you’re struggling to get your community to do something, it’s probably because you’re telling them to do it. This doesn’t work too well. It relies too heavily on your influence over the collective influence of the community.
If you want members to take an action, begin small. Reach out to a group of people and persuade them to start doing it. This doesn’t have to be an influencer group, just members that believe in it. Soon others will join in. In short, you need to show them, not tell them.
For example, if you want members to share their best pictures of …. You reach out to 10 (or so) people and begin doing. Others will soon join it. It becomes part of your community culture.
If it doesn’t take off, you know it’s not something the community wants to do and you stop trying to get your community to do things they don’t want to do
This takes time and planning. This means you need to be picky about the steps you want members to take. Only pick the most important stuff, ignore the rest.