Step 1 - Get the tools: a timer, a piece of paper, and a pencil
Step 2 - Turn off distractions, and be clear on what piece of work you're going to do
Step 3- Set the timer for 25 minutes
Step 4 - Start working, really focus, and just work. During the 25 minutes, if something comes up that could distract you, make a note of it on the piece of paper and carry on working
Step 5 - When the timer goes off, step away from your work