Start with some of the free tutorials on this site to get yourself orientated with Lightwave. Then move on to some of the more advanced ones such as the Lava Lamp, Creature Feature, Strat, etc.
Also, dig around in Modeller and Layout in your spare time - search through all the menus and really get to know all the tools that are available to you - just playing around with primitive shapes so you can get a feel for the tools full effect.
Finally, post your work up here for (constructive) criticism and comment - we won't bite (much)
