Compiled Bindings is a way of telling Xamarin.Forms at compile time the type of data the binding is going to be using. This is means that Xamarin.Forms will not have to use any reflection at runtime to resolve the data binding, which means better performance, and who doesn't want better performance?
Boost Performance with Compiled Bindings in Xamarin.Forms by James Montemagno
Iconography is becoming a hot topic in mobile app development/design. In this post from Synction, Selva takes you through the why, where and how of getting started with icon fonts. Selva also shows a great tool called Metro Studio, and how you can create your own icon TTF files from it... who knew?
How to Use Icon Fonts in Xamarin.Forms App? by Selva Ganapathy Kathiresan
ICommand play a very important role in MVVM and it is usually an important feature in all the popular frameworks (MVVMLight , Prism , …) and even the default xamarin forms implementation. The main problem of the populate ICommands implementations is async support. Learn how to overcome this.
Async Command A Modern Implementation of ICommand by Ahmed Fouad
Navigation is one of those touchy subjects amongst MVVM developers / advocates. Xamarin.Forms having View-based navigation doesn't help. Nick Randolph knows A LOT about MVVM and in this post, he discusses the ins and outs of different navigation approaches in MVVM.
MVVM Navigation with Xamarin.Forms Shell by Nick
Visual State Management is a concept from Xamarin.Forms 3.0 that allows you to define how components on your UI look based on state. For example a form, it might be that you change the colour of an entry if it has focus. Charlin takes you through the why and the how of visual state manager.
Understanding Visual State Manager in Xamarin Forms by Charlin Agramonte
If you are developing a mobile app, it's worth enabling VoiceOver on iOS and considering the usability from the perspective of people who rely on these tools to access your app.
Xamarin Forms Accessible Headings by Stuart Lang