I have been writing for the better part of thirty years... and I gotta say that I have only experienced what folks call "writer's block" a few times and that was very long ago.
The way to not have it (in my perspective/experience) is to simply begin by writing a single word... then another word... and another... and however many it takes until a sentence forms... and see what emerges from there.
If that does not work for a given person's personality then yeah you are providing some super sound advice here @jongolson and I concur that folks should write what they are passionate about and what they know and/or are learning about!
Never have to struggle to find the words, if we love what we are talking about!