The way I got into modeling was by taking a class back my sophomore/junior year in high school. We primarily used Sketchup. So I usually use sketchup, however I can and sometimes use Blender and I recently downloaded Maya which I am learning.
As for teaching yourself I would recommend watching some tutorials (don't watch the really long ones where you begin to lose interest) just some that are short, sweet, and to the point.
Going along with what Mkingy said, be sure to start small... the first model I made was a cup. You can then move into larger and more complex models as your knowledge of the program grows.
Remember modeling is trial and error. Be patient!
Hope this helps!