One of the most important parts of the design process is translating your thoughts and ideas into something that experts in their fields (i.e. programmers and graphic designers) can understand and work with. Two important areas must be covered to get started: the product specification and the mockups.

This artifact can exist as a text outline, flow chart, concept map, or any other organizational structure. The idea is to detail every part of the app in this document. It not only helps the people you work with understand your vision, but it also helps you figure out potential gaps and identify needs.  This also helps you communicate to developers and graphic designers what your requirements are, and thus they can help give you a firmer idea of the costs. Dan Saffer's Designing Gestural Interfaces is a good resource for beginning designers, but I found it was helpful for thinking about every possible way an interaction might take place on a touch screen device.

I chose to do a text outline to organize the different tools in Explain Everything and outline their function, but I then spent a lot more time doing mockups of each tools individual menu.

The specification evolved over time once the design process began. New feature ideas emerged, and with those new bullet points and corresponding mockups.

Using standard elements at first can be helpful for the initial phases of design when you are trying to get the functionality down. Once all of those pieces are sorted out, then you can know for sure which pieces you want to get custom graphics for. Below is an example of the Draw Tool pop-out menu for Explain Everything. On the left is the mockup which I created, and on the right is the actual current Draw Tool pop-out menu.  The Pop out frame, background, header text, 'Set' text options, and slider, are all from the standard SDK. The color palette, the thickness options, and pen tips are custom graphics.

Below is an example of the home screen for Explain Everything.  All of thexe graphics had to be custom made, but at first it was important just to get the functions working, and once happy with how the buttons worked and were position, the graphic designer was able to make something great out of it.

This part of the process is definitely the most time consuming, but at the same time its the most important to get right. Front-loading the effort into the details early on will save lots of headache later on.