Try this tutorial...
A (sortof) friend of mine developed this tutorial that may help you with that issue
https://www.geocities.com/jozvex/tuto...rparticle.html
It will give you tips on other things as well, such as accumulation etc.
Good luck, and I hope I'm not too late!
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com