Some specific ideas from what I've noticed (mostly in the User Guide):
2) The User Guide references the Wiki (I'm guilty of doing that myself). I think it would be beneficial to move any referenced information to the User Guide and Developer Guide so that a single release's guides has all of the information.
3) There appears to still be some ambiguity to what belongs in the Wiki vs the User Guide. One possible approach would be to move any Wireshark-specific guidance from the Wiki to the User Guide and then remove it from the Wiki. (note: this has overlap with #2)
4) Standard proofreading and reviewing for clarity and accuracy.
5) Update screenshots from GTK UI to QT UI . Document (in comments) which files were used to create the screenshots.
Moshe