1. Create a splash screen
    • Avoid writing code in OnStart of the app
    • Instead create a separate landing screen and add a timer control of 5-10 seconds
    • Till the timer get's completed, load all your basic configuration in collections
  2. Variables
    • Make sure to use the "UpdateContext" wherever possible instead of "Set"
    • Avoid use of "Set" function because global variables can be updated anywhere on the app which may break the functionality if not used wisely.
  3. Avoid lot of controls on a single screen, this may impact the app performance. 
  4. Use meaningful labels for the controls. This will avoid the human error while doing the relative operations based on control properties.
    1. Example: txtPropertyName instead of TextInput_1
    2. Example: ddCity instead of DropDown7
  5. Avoid updating the collection inside the gallery if the same collection is being used as a data source of that gallery. If we update the collection, the gallery will not show the correct data every time.
I will keep updating this list as per my experience.