The 50mm prime suggestion is not just that it's sharper (which may or may not matter except on larger prints), but that it's a terrific tool in two ways:
1) it forces the photographer to be more involved in taking the photo (as opposed to just cropping in the viewfinder without moving), so it's a good learning and development tool; and
2) it's usually an f/1.8 lens or better, so, being much faster, it opens up a lot of possibilites, from using slower films to existing light. Even the best, most expensive "pro" zooms are more than a full stop slower.
Zooms do have the advantage of convenience, no doubt about that.