You could use cymbal springs for your chinas. Also make sure you're hitting your cymbals correctly..
Paiste Cymbals: Frequently Asked Questions check the "Correct Playing Technique" You need to almost "swipe" your cymbals instead of hitting them straight down. Now you can't do this really if your riding on your crash or china but for quick hits its a good thing to keep in mind...
For the hihats, make sure you're not hitting them perpendicular with your stick..aka dont hit like this --\ (the \ being your stick) but instead hit the same as you would your crash cymbals.. (i can't make text look correct so I hope you know what I mean)
Also, do NOT over tighten your cymbals. Not only will it choke them, but make them crack quickly.
Best of luck!