You think I only change the texture? lol
I usually make a new material and texture first (doesn't take long) and then I change direction, speed, colour range, add effects and other stuffs. You can also put different particles into one script, I never tried that though.
Take the confetti rain for example, it has a grey texture, but in the outcome every piece has a different colour. Also it falls as if someone was throwing it (small break, then lots of confetti, then another break and so on). Script something like that in a few seconds, then come back~