How do I successfully sell photography to magazines, and which ones?

[eriicasmile]

I know I can send in packages directly to companies, but how affective is that going to be? I also know I can call in and talk to someone myself, but again, same concept. Are there any magazines that are going to be more likely to accept and use some of my work, than others? (Ex: An animal wellness magazine compared to a magazine like Allure.) If so, how do I get a hold of such companies and which way should I do it? Most of my pictures that I was thinking about sending it, (or trying to), are of animals and/or nature. Do you have to be a certain age or have certain degrees or anything along those lines in order to do things like this?

Any advice, help, tips, anything is very much appreciated.