Tips to start speaking at conferences?

So I was lucky enough to talk at RedHat DevNation in SF a few years back, and although they bungled the audio on the recording overall I had a great experience.

This week I attended The Lead Dev conference in London and it was awesome and really inspired me to have another crack at conference speaking. I'm a confident public speaker and so I'm not worried about the talk itself.

I was hoping the community would have some hints and tips on finding speaking and panel opportunities? Last time I just googled around to find relevant conferences that had a CFP open. Surely there's something better? Is there a site somewhere that lists all the CFPs that are currently open?

And a bit of a stretch, does anyone who's been asked to speak (e.g. direct request as opposed to CFP) have any tips on what they've been doing (social media, blogging etc) to get a profile so conferences come to you.

Thanks in advance :)