I let my ideas come to me. In the notes section of my phone are dozens of insane, nonsensical things I've jotted to myself. Sometimes they come to me in the middle of the night, sometimes when I'm out drinking with friends, sometimes at work.
I deal with writer's block by avoiding the opportunity to hit it altogether. I sit down and write like clockwork most every morning, and I usually have developed a clear idea of where I'm taking my story. Sometimes it's just a single page of forward writing before I run out of that vision I had. At that point, I'm done.