Make a list of 5 things you need to do.
For each thing, look at how simple it is and how you might write the code for it. If it's complicated, break it down into at most 5 more steps. Keep going until everything looks simple.

Eg, making tea.
1. Boil water
2. Add tea bag
3. Pour water
4. Add milk and sugar
5. Drink

So
1. Boil water
might be
1.1 Open kettle
1.2 Open tap
1.3 Add water
1.4 Close tap and kettle