Without any ado, here it is:

1. List down each thing to be done for any activity, without worrying about organising it.

2. Order it in sequence. Some activities can be done parallelly.

3. Add details like roles, observations, etc. This is every other things that anyone could need to do that activity perfectly.

4. Update it as you gain more experience in that activity. It should be kept updated by the person actively doing that activity.

5. Have someone else (who has never done it) use that SOP to see if they can do the activity just as well. If not, just fill in the blanks.

Keep this up till there's nothing left to update.

Happy SOPing!