I've written a blog post recently about our Bitcoin Ljubljana meetup, it doesn't really have tons of tactical advice but might serve as an inspiration

It depends a lot on the crowd, personally i think doing presentations every time is a great way to bring in new people - its easier to go check out a topic that you're interested and then stay for drinks after than just grabbing drinks with strangers. Give new people things to talk about if they are on the shy side.

But it can be annoying to beg people to make a presentation every month and you might end up doing quite a few by yourself.