As someone else replied, contacts, friends and old colleagues. I got my first remote job by going to the local Ruby user group and getting to know people.

You might also check https://weworkremotely.com/ (full disclosure, company I work for runs the site).

I found remote work through old work contracts. People that trust me to do a good job regardless of where I am. It is difficult for companies to give people that trust, so it is all about helping them to find that trust and then not letting then down.

Get an offer first. After that then say you'll only work remotely.

That is pretty funny solution, but it might just work sometimes. How much has that worked for you?

Shameless plug https://github.com/lukasz-madon/awesome-remote-job

Why not find local work and then start a company you can run remotely?