Two things well maybe three. Glass is everything, spend your money on great glass. Whatever you do get an aftermarket book on the camera body. A person really needs to decide how deep into the camera operation they want to go. That truly depends on your photographic knowledge you currently have and then how much you want to learn. And lastly remember the multiplication factor for the lens. Most entry level camera bodies have a 1.4 to 1.5 factor because of the size of the sensor that the picture is recorded from. A 100 mm lens now becomes 150 mm. So when you get into the 300mm lens, very few people can effectively hold it steady when it now becomes 450mm cuz of the factor.
Greg Luer '85 4Runner, '89 FJ-62