Wonderful of you to offer! Follow-up hasn’t been weak across-the-board but it’s certainly a hard thing for organizers to juggle on top of everything else.
We have limited resources set up for this at the moment, such as: a) the ability to reach out to Harri for local group advice and funding, b) copies of Doing Good Better you can use for a book club, c) the chance to request EA Global tickets to raffle off, d) a series of follow-up emails to attendees, and e) brief advice for running a follow-up event (https://goo.gl/w9fkYS).
Happy to take suggestions for other things we might do.
In brief, large speaker events and workshops, depending on the needs of a local group. Perhaps self-evidently, large speaker events are best for nascent chapters trying to attract interest; workshops for augmenting the engagement and/or skill of existing members. There’s some information about this in the Organizer FAQ, as well a prompts about this in the EAGx organizer application and on the “Get Involved’ tab of effectivealtruism.org.