Things will break! Test/prototype things early and often. Break things before they break you.
Identify a minimum viable product (MVP).
Create a plan for the fabrication of your mechanical parts early.
Minimize the wire length between your octal buffer and your LED displays to reduce noise. Do not braid your signal cables.
As you start integration, make sure that your power supply can provide enough current to all your components.
Always check the power supply first when your previously tested components start breaking.
Make sure your circuit board is easily accessible during and after assembly.
Buy wires, tape, and solder up front so you don't have to pay by the foot at SPDL.
Even simple tricks can impress people- don't overcomplicate.
Test subsystems incrementally.
Keep your circuit diagram up to date.
Support each other!