When an amateur takes a shot of a flower, it's usually from five feet away. That's fine. The pro, however, will then walk 3 feet closer, then take the shot. And, then, walk 2.5 feet closer, and take another shot. And, then, walk so close the lens becomes a part of the flower.
The real lesson, of course, is that you should just walk right up to the subject and get in so tight that the camera can't even focus (if that happens, back away an inch or so, buddy). Rarely, do you regret wasting digital film by taking close up shots; in fact, you usually wish there were more. So, make sure you get right up to the very thing you're shooting. If you're shy, wait until the crowds have gone or invest in a good telephoto lens. I prefer the former (it's cheaper). :P