I have been doing quite a bit of work over the last years on online engagement in relation to public policy.
One lesson learnt is that at the core of it, you need to create a restricted group of people who actually enjoy to get together, discuss and collaborate on policy issues. You only need 3 or 4 people, but they must be interesting and relevant to each other. Getting these people together already means to act “as a platform”.
They should start collaborating in public (social media), and slowly, engagement can grow organically. And It helps if they have a good sense of humour. The idea of “fun” is often seen as opposite to “important”: but as I learnt from Rik Torfs at TEDxBrussels, we can be “light but deep”.
For this, you need to frame the challenge in an interesting way. It should be meaningful to users, not only to the promoter of engagement.
This is arguably the most difficult part: what people want to discuss is often different from what government want. This is why it’s important to let participants frame questions and discussion: the symmetric participation I referred to in the past.