I would recommend writing apps as much as you can from "scratch" (do use standard libraries for your language, but shy away from big libraries or platforms that aren't a core part of the language). I think this helps ensure you're not just wiring things together but are truly creating something out of thin air and thinking algorithmically. That experience will serve you well when one day you're confident in piecing together ready-made libraries, platforms, and your own code to create your projects.