I love starting a 206, I have been flying the 429 today all FADEC and really cool, but there is a great feeling lighting up a 250, simple rules
Good Battery
Try and avoid wind down the pipes
Cool below 150
Give her plenty of N1
Know the difference of a Bendix and CECO
Assume it may get hot and be ready
Don't panic if it does, close the throttle continue with button
If you find she is too hot, or too slow then tell engineering, time it, give them the figures and adjust the start, but always measure the start from cold with no ground power to prove an accurate figure
I have started many 250's over the last 27 years, don't over think it