Practice. Other than the lights, it's all about making the car go. Run out each gear fully and shift quickly. Live on the edge of wheel hop on the starts (do you Quaife?). Above all - always go as straight as you can.
Your Mustang story reminds me of running a 60-something Vette (prolly a 289 or smaller) to a clean heads up win after giving him a head start at the light. Feels good to actually beat a classic every once in a while.
