Microsoft has published its design guidelines for building Universal Apps on Windows 10. The new documentation outlines designing apps for Windows 10 on PCs, phones, and tablets.
The guide is split into three primary sections: Design basics, Guidelines, and Design downloads. Design basics covers the fundamentals of designing for multiple screen sizes. You can get a primer on different phones, tablets, and PCs, and follow Microsoft's process for planning an application.
The Guidelines section covers best practices for everything from animations to user interactions. It breaks down into articles on specific aspects of each section, such has how to add and delete animations, set up app contracts for location-aware apps, and more.
You can also download a number of templates to get started on designing your Universal app. The templates have date pickers, icons, and more. You can download templates for PowerPoint, as well as Adobe Illustrator. You can also grab the redliner tool for Adobe Illustrator.