The best advice I can give to UX designers is to make bold choices. Make choices for your users. Leave lots of stuff out, and don’t be afraid of reading an angry review demanding feature X to be added to your product ASAP.
… one day without understanding how feature overload will inevitably make their life more difficult. Great designers need the arrogance to ignore what users say and design for what they need. And this often also involves confronting product managers and marketeers.
… are typically part of the main flow and don’t get in the way. Somewhat-handy features are suspect. If in doubt: leave it out.