What problem does this solve?
When a software, a tool, goes online with its first release it's not always complete. Moreover the use made by its community has an impact on where the development should go. Maybe the users find not so clear a point or unfriendly another, but also they can have some ideas about missing features widely wanted (or not). If you want to catch these feedback you need a space for collecting them and some channel where you can be contacted. In fact every user has a different approach to communication: i.e. some prefer anonymity, others are bolder, some are accurate, others are prolix.
What is the solution?
The simplest and most concrete way to collect features requests is to have an issue tracker (like the one that Github provides). After you have choose your favourite environment remember to leave some references into your software, for example using FAQ or contact pages. Don't forget to use different approaches, i.e. providing an email. In a Wikimedia context is also important to have a wiki talk page (on meta or in the wiki project that fits most).
Things to consider
- Users will feedback you in a non systematic way, so is up to you to harmonize all the ideas into your issue tracker or to encourage them to use it.
- It is important to consider that not all users will have technical knowledge, and thus to provide a method of communication that does not require it (e.g. forums).
When to use
- Every time you want to receive suggestions from the community that use your software.
- The Wikimedia Commons app for Android uses Google forums and GitHub for feature requests and communication with users. 
- Having a channel for user feedback is essential in order to maximize the impact of development time. Misaochan (talk) 03:59, 3 October 2016 (UTC)
- Grants:Learning_patterns/Volunteer feedback and follow-up
- Grants:Learning patterns/Git repository for software