Loose as ever to let them breath their natural tones. I use widgie rubber type washers on the bottoms and the smallest felt i can find, on the top.
http://www.wedgie.com/cgi-bin/ccp5/c..._detail_cymbal
Exception is my china which i use i felt below and two on top so it is reasonably firm so it doesn't wobble too much when played in it's upside down position (or is that right way up). Never broken a cymbal in my life.
IMO thinner cymbals that are tightened right up are more at risk of breakage than heavy weight, the vibrations are the greatest at the bell, so all cymbals must not touch the metal of the stand and if too tight the vibes are transfered to the outer weaker edge. A heavy blow at the wrong angle risks a crack. Always play with a glancing blow unless your'e loaded. The cymbal manufacturer sites tell you this which is good of them, imagine how many repeat cymbal sales they would get if all drummers smacked their instruments on the edge $$$.
