The best thing to do is to sand the rims down, to give a nice texture, or if you really want good braking cut very small grooves in your rims with a hacksaw all the way round about an inch apart, its what my mate did and i have done it on my BMX and it does work, however it shortens the life of the rim and the block considerably! do it very cautiously - YOU HAVE BEEN WARNED.
The good - Chain reaction Cranks came the next day, and with £20 off the list price and free postage!
The bad - Julies cycles - 3 weeks for a chain to be despatched!!!!!!!!!!!!!
The Ugly - Halfords - the guys in there are too busy pullies stoppies on Saracens to bother to serve you and when they finally do they (in my experience) have no idea what they are on about.
It has to be made of reynolds 853, has to be either flouro pink or orange, and HAS to have be plastered in stickers. Try to go for a nice head angle to make it handle well, even if you run long travel forks, and make sure it has a disc mount, for long term upgradability ;-).