I'm doing this for money, so I prioritize based on that.

I put everything that I think would be cool to do in a doc. Then I add from 1 to 5 $ signs next to each task depending on how much money I think the task could make, or a ? mark if it has questionable financial value.

For example:

"Optimize documentation pages to rank better in Google - $$$$"

"Improve styling of download links table. - ?"

Then it's really easy for me to decide what to do.