Meetup organizers tend to always be on the lookout for new speakers. Start with a 5 minute lightning talk and then offer to be a regular speaker on smaller topics until you are ready to take on a 15/30/45 minute talk.

Some of the more common lightning talk topics I've seen is:

"5 random {{language}} tips" "5 things you didn't know about {{language}}"

They force you to be on the lookout for oddities and to do your research.