1. To use writing as some kind of therapeutic tool works out for me. When I feel down, anxious, heartbroken or have a bad day, I try to write it all down, and not to care too much about the lack of rhymes or making sense in my text.
2. If you have a melody in your head, record it immediately on your phone or computer, so you don't forget it.
3. When you get up in the morning, before getting dressed, drinking coffee or eating breakfast; sit down and write for one hour. It is good because you're, in my experience, less critical then and your mind is not yet exhausted.
4. Writing for say, 10 minutes, without lifting your pen or thinking about what you're writing is a great way to get into the flow.
5. Dare to perform it to someone. No matter how stupid and embarrassing it seems (because it always does), just do it.