Bug reports, feature requests, or anything else about the software.
Include the app name and version number (shown on the project page), what you were doing when it happened, and what you expected vs what actually happened. A screenshot is useful if there's a visible error message.
If the app crashes on launch, try running it from a terminal so you can see any error output before it closes.
A short description of what you want and why it would be useful. I can't promise everything will get added, but I do read everything and most of the features in these apps came from using them myself and noticing what was missing.
I'll usually reply within a few days. If you don't hear back within a week, feel free to follow up. Sometimes things slip through.