Australian novelist Fran Cusworth has a simple technique whenever she's planning a novel: she gets a calendar and writes down a target number of words that have to be completed on each day.
Cusworth, who has published two novels (The Love Child and Hopetoun Wives) with Penguin and is polishing on the second draft of a third while working on a PhD and raising two small children with her husband, explained her technique at a writing time management course I attended in Melbourne this week. "Set yourself word counts to the end of the year," she said. Cusworth uses an erasable board so she can adjust those totals as circumstances change; you could get much the same effect by using your preferred calendar application.
While Cusworth advocates the technique for creative writing, it's just as useful in a work context. In more extreme circumstances, you can use the same approach with a much shorter time frame: set yourself targets for every 15 minutes and try to eliminate all other distractions (tools like Typewriter or WriteRoom for Google Docs can help with this). For a long-term project, remember when you're done to finish mid-sentence so you can start off easily next time around.
What's your trick for beating the writer's block blues? Share it in the comments.