Don’t make substantive edits to posts. Don’t edit out errors other than typos. If you change your mind, write a new post, and you can also add a small note to the first post about the update. I added text about this to the FAQ. It’s OK to edit in minor notes or minor wording changes to improve clarity. It’s OK to add some extra thoughts at the end of your post, soon after posting it, if they don’t change what you already said.
I’ve also edited the forum settings:
trust level 0 or 1: posts editable for 90min (down from default of 1 day)
trust level 2+: posts editable for 1.5 days (down from default of 12 days)
max edits per day lowered to 5 (more at trust 3+. default was 30 with more at trust 2+)
In the future I may further reduce editing limits or just disable editing. I do think strictly no editing allowed has advantages. It might be better overall (opinions welcome).
A downside to not allowing edits for a longer time period is it’s harder to edit in notes based on later discussion, e.g. that you changed your mind about a post, concede it’s wrong, retract it, etc. You can only add updates in child posts (which are findable – Discourse has a feature for showing replies to a post).