Where to start? Somewhere. Anywhere. Just begin.
When you're looking at a blank page, crisis can strike. What if the first stroke isn't perfect? What if the idea doesn't come across? What if...
Life is action. Art is expression. Start moving. Get something going. Make a mess and clean it up later.
My favourite advice for the tormented perfectionist (which is often me) comes from David Ogilvy:
I am a lousy copywriter, but I am a good editor.
With Ogilvy's advice in mind, I try to break my work up into different phases:
1. Messy & Mundane
In this stage, focus on freeform creation. Don't hold back and don't edit. Just let stuff pour out of you. Get that page full of words / paint / code. Make stuff and withhold the criticism. When you're done, step away. You'll come back to it later.
2. Refined & Recognisable
Now it's time to revisit your work and edit it down. Less is more. Go over it and try to find the red thread, the hidden gems. I copy and paste a lot. Reworking and reformatting what I originally wrote. Get good at this and you'll find it much easier to product good stuff, at speed.