Dave,
The way to start any project (at least any project which is going to take more than about 15 minutes) is to go through a deliberate and thorough design process.
Start with establishing the specifications which the program/system must meet. Define inputs, outputs, functions/processes, special requirements like timing, regulatory limits, safety issues, and what (and who) determines success. Then design the program. Task lists, flow carts, state charts, and other documents can be very useful.
This is top-down design.
Sometimes bottom up is also important. Here you may make little test programs or part which may later become subVIs to determine how things actually work in the real world or to demonstrate some feature. Trial GUIs are often helpful if the end users have not been exposed to programs like this before.
Last, write the program.
Lynn
