How do I prepare for hills?

[alpinerabbit]

I promise it will get easier.

Try the same route a few times and you will notice. Some of this effect is psychological, especially if you just start out (btw I started serious riding in September. I speak from experience).

As the above link says, alternating between standing and sitting will give some of your muscle groups intermittent breaks and you can go on longer.
Apparently Lance positions himself very much above the handlebars, using some arm muscle to support his upper body. who knows if that helps. I've also heard him quoted that he does not see the hill, just the 10 meters of road in front of him. This definitely seems to work for me.