Zbrush is not the easiest application to learn to model with. It's method of going about modeling is a little bit unorthodox.
I'd recommend it for masochistic beginners, and little more advanced users.

Wings is a good and in poserdom pretty widely used free application for 3D modleing.
When it comes to short learning curve affordable little applications, I tend to use hexagon - even though I have 3D max too.

Good thing to start learning is going to be subdivision modeling. If you do some searching on rendo and other places, there's a lot of tutorials that cover it's basics. I've even seen instructional videos for it on YouTube.

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