See
http://ecomodder.com/forum/showthrea...gine-1141.html
I always clutch start one or 2 gears higher than I would normally be using for cruising at the current road speed.
In a quick motion, I nearly fully release the clutch to spin the engine up, then immediately depress the clutch again. The engine will start, and it settles to idle while selecting the appropriate gear (for the road speed/power requirement) to do a smooth clutch re-engagement with rev-matching, if necessary.
Some people say they can just "dump" the clutch in the proper gear and all is well, but it's not as smooth as doing it the way I described.