FIRST:
What macro subjects are you most interested in photographing?
1. It just sits there (product photography, copy stand work, abstract still life, etc)
2. It moves a little bit, but ignores you (flowers, plants)
3. It moves a lot, and may not want to stick around (insects, spiders, small vertebrates, etc)
For #1, a 60mm f/2.8 macro lens is just fine on a crop body. Working distance (front of lens to subject) is quite short. I use this lens a lot at work, to photograph pathology specimens (all together now, EWWW)
which, having been removed from the owner by a surgeon, are definitely Just Sitting There on the copy stand. BTW, if you use a copy stand or tripod equivalent, you don't want to get a longer lens if you do any near-macro work.
#2 subjects can be handled with any focal length macro.
#3 subjects are best handled with as long a telephoto macro as you can afford, for maximum working distance. Some critters don't like it when you shove glass close to their probosci, and leave for more secluded environs. Insects are very sensitive to motion, and they have wide field of view.
One thing a beginning macro shooter ought to acquire is an adequate tripod for their shooting, or at least a monopod or a long pole (google "Lord V beanpole" for a photo of the pole technique). Monopod / pole users tend to focus by tiny tilts of the pod/pole, not by the lens focus ring.
A second thing to consider is lighting. It gets rather dim at 1:1, and you need slow shutter speed in many natural light conditions (hence the value of the tripod/ monopod/ pole). Some people use various flash set-ups for fill or primary lighting. See Fred Miranda macro forum for the thread "Show your set-up" for a large number of creative DIY ways to use flash effectively.
If you want to start on the cheap, get a cheap adapter on eBay and mount an old 50mm lens (manual aperture ring, any mount) backward on your camera body. You lose the EXIF and some automatic function, but images are OK. This is how I started on macro back in the film days. Extension tubes and front-filter-mount accessory lenses are another way to convert a non-macro lens to a macro lens on the (relative) cheap. Go look up the macro section on the "Cambridge in Color" website for simple explanations.
GO FORTH AND HAVE FUN!