For me its a case of feeding in the clutch and the power at the same time with the right amount of each.
I'm one of those that is constantly blipping the throttle while I wait for the lights to change, then as they go out pull back the throttle and start slipping the clutch lever and feel for the bite, as it bites its a matter of feeding in the power as you engage the clutch being careful not to bog the engine by applying to little power and to much clutch
I use to be a lot better at it when drag racing at Santa Pod and Avon park back in the early 80s but racing the 916 in SoT with its hoppy dry clutch ruined my starting technique.
There is a nice set of traffic lights just up the road that are great for practicing your starts, just be carefull Bradders isn't next to you