There is a distinction between wireless triggering and radio triggering, wireless is when you use one flashgun to trigger another, radio triggering uses radio signals which means you don't have to have the light from the camera position which you often don't want, the radio triggers will also have a much longer range.

If you want to maintain TTL then it's an expensive exercise. You will need Radio Poppers or Pocket Wizards and, good though they are, a pair will cost more than you paid for the flash.

There is another, much cheaper way to go and that is to use manual everything then the radio triggers cost around £30 per pair, about a 1/10th of the price of Pocket wizards, a manual flashgun around £60 each. Note that the vast majority of studio lights are manual anyway, there's no advantage in using the TTL triggers with these.

TTL is great at automatic 'fill in' flash, it can get complicated when anything other than that is needed, then manual everything scores you have much more creative control, but you will have to set the exposure manually, with practice this is not really an issue, with a flash meter it's more accurate than TTL, it's the way I learnt many years ago and the way I usually work anyway.

See this site for more details

http://strobist.blogspot.com/

It's grown into a huge site a good starting point is the 101 Archive.

Chris