Partner project using WMF.
I learned to simplify tasks. Clear and open communication with my partner was critical, especially when we had finished the "easy" parts early on and then each had markedly divergent opinions on how to proceed. We addressed our differences of opinion almost immediately and from there we were able to move forward in a much more cohesive way to create a good end-product.
Skills I learned: Creating a WPF, data binding, understanding the MVVM and how each part of it works.