Continuing to work with the Lunch Money Buddy application has been a great practice in drafting wireframes. Wireframing is an invaluable skillset for UX practitioners because it is the first real step towards taking ideas from concepts into real world designs. It forces the designer to think how something would actually work as functional software. Often times the simplest designs can be the most challenging, and the more practice in developing wireframes can help to identify and put into practice effective techniques.
Designing for mobile is particularly challenging for several reasons. The biggest challenge is effectively managing limited screen space that is available to the designer. But even after accounting for screen space, multiple orientations need to be considered as well. With continued iterations, it becomes easier to strike a balance and create a user-friendly interface.