Voice And Tone: best practices for the writing in your app - how do you create a clear, appropriate voice?
Balsamiq: great tool for low-fidelity prototypin and wireframing. Note: we have a class license for free.
inVision: create prototypes for web or mobile. Lots of integrations. Note: we have a class code for free unlimited use until 6 months after you graduate.
How Does Balsamiq Compare to Other UI/UX Tools? Includes Visio, Keynote, OmniGraffle, Gliffy, Moqups, Pidoco, WireframePro, Photoshop, Illustrator, Sketch, InVision, Marvel, Flinto, Axure, Adobe XD, Figma, UXPin, Proto.io, Web Frameworks, Visual Code Editors, etc.
Adobe XD: Adobe's new interface design tool. It just came out of beta and if you have Adobe Creative Cloud I suggest you try it out.
Marvel: create desktop and mobile prototypes. Integrates with Sketch. Nice free plan.