And, of course, as everyone so far has completely neglected to mention, there are the excellent tutorials here at SLW.
Start out with some of the more simple free tutes, such as the coffee mug, introduction to layout, ocean scene for instance. Then think about getting the stratocaster tutorial (it's currently on special - see the home page). What you'll learn from this will be more than enough to set you on the way to mastering the software.
You'll also want to obtain some books (both Lightwave and General 3D one as well). Check out
this thread for more details...