I simply can't get Frontend editing to work, but it works for all my non-K2 articles...

What I have done:
- create a K2 user
- assigned K2 user to K2 Group with Frontend editing access

What else do I do, and where should I be able to see an edit button?

cheers
schmaka

This K2 user can edit all items or only his own? If you have selected only his own through the User Group parameters make sure that this user has items he has written otherwise he won't be able to see any button.
An Add button appears in the category box, if you have it enabled and an Edit button right next to the title either in the category, user, item pages.

Also it would be helpful if you used the K2 User module for Login and not the default Joomla! Login.