Media Buying

I would like to get into media buying. I know its basically placing banners on websites. But where can I learn to do it? Im looking for a mentor or a site that teaches it.
Or is it just a matter of learning it yourself by doing? I have been reading other forums and they say that you can lose money quickly if you don't know what your doing. This is whats stopping me from diving it and learning it on my own. Ive also looked at youtube videos its helped a little. I would like to learn on my own…
Media Buying

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