I had planned on writing an extensive particle tutorial, but have never had the time. I did have most of a demo capx ready though. So I am uploading it here as a place to grab ready made particles. (That's what I've been using it for the last 6 months.)
It uses the r153 release, as I had to fix a few that I had broken using it for parts.
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Updated and added a second Capx. It is a modified version of the original Particle demo.
Even more fun to play with. (Mod uses r155)
While particles have been adjusted for fun, is mainly using a trick where the background doesn't erase. Using a nearly transparent sprite over the background, we control how fast it fades out. Or using the layer opacity, how much stays permanently.