Is it better to tour the Red Light District on your own or to take a tour?
You don't need a tour. It's easy to do on your own, Rick's Amsterdam guidebook has a self-guided tour of the RLD. Alternatively, if you follow around one of the many British Hen/Stag groups...they'll be happy to give a free tour:)
I agree...you can easily do it on your own.
Just don't take any pictures.