Design+Code - Learn to design and code React and Swift apps
Sketch App Crash Course - YouTube
Sketch Hacks: Little Tricks to Improve Your Sketch Workflow - UXcellence
Keyboard Shortcuts for Sketch App
Advice: learn symbols, nested symbols, text styles, layer styles, and style libraries sooner rather than later. This will keep your projects DRY.
How to Automate Creating Text Styles and Layer Styles in Sketch