I can't draw and I've been creating various 3D scenes and models for quite a while. A drawing is just a source for inspiration, you can easily use photographs, blue prints, etc. If I was to make a career out of modelling, I would include an art class as part of that just so you would learn more about shadowing, camera angles, anatomy, etc.
There are dozens of economical programs for modelling available without having to dump a lot of money. A good question to ask yourself is what kind of things do you want to model? Most packages excel in one area or another and knowing your goals can help your to decide which tools you will need.
Learning to use 2D graphical editors in order to make custom textures is also an essential part of the modelling skill set.
Learning character animation is a subset of modelling and is a highly sought after skill.
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TAZ
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