I agree with Tony wrt composition and using primes. Really forces you to think. Of course, it's sometimes hard to move around to do this in some club, restaurant, or festival applications. When there's a sufficiency of light, or the working distance is fairly far from a stage, zooms do have application in these situations.

In terms of the lens focal length, complicating things very slightly are that many 35mm DSLRs have imaging sensors that are smaller than a full 35mm film-frame. What happens is that the Field of View (FoV) becomes cropped, in that less of the output image circle from rear of the lens is actually seen by the imaging sensor. For the case of APS-C sensors, the FoV factor is 1.6x, and ASP-H, it's 1.3x. For a full-frame camera, of course it's 1.0x.

This cropped view on APS-C/APS-H cameras is essentially image magnification. For a camera with 1.6x FoV, the 70-200mm zoom lens works as if it were a 112-320mm lens. It does this without any optical loss as well. Kinda neat to get more "reach" for "free." But there's a downside, and it's at the wide-angle. A 24mm wide-angle lens works to an equivalent 38mm, which is not really wide-angle any more. For the EOS APS-C cameras, Canon has developed EF-S zoom lenses to work much better at the wide-angle end. These lenses have their last optical element protruding out from the lens body farther, in order to be closer to the imaging sensors. In compatible cameras, this mitigates the FoV effect quite substantially, and the zoom ranges are rather useful.

In terms of primes, on a 1.6x FoV camera, a 35mm lens becomes equivalent to a "normal" lens at 56mm. And the 50mm "normal" lens becomes a little bit stronger, equivalent to a 80mm lens.

One nice thing about the FoV issue is that if you have more than one kind of DSLR camera, then one set of your lenses can have multiple uses.