For a newcomer there is no better place to start than with the videos. If you've turned off the Startup screen, then you can access it again from the Help menu > Welcome to SketchUp. Go to the movie tutorials and work your way through them. You'll be modelling stuff in no time.
The first video talks about the navigation tools, but if you have a scrollwheel mouse you can forget about using them...Press wheel and drag mouse is orbit. Same again but holding down Shift is pan. Scroll to zoom. It's as easy to navigate as a video game.
One thing than stumps newbies is that the cursor position is sensitive to what's behind it on the screen. This means that you'll zoom much faster if hovering over something some distance away, than if you're right up close, or the mouse is over nothing but fresh air. This feature also makes it virtually impossible to orbit until you've actually drawn something, as there's nothing to orbit around. Maybe that's why they include a figure in the default template.
Once you get the hang of things, you can set up your own blank file with your preferred settings...like units and shadows...and save this as your default template which will open every time you start a new file.
EDit: I just checked out a couple of those videos and they seem to be a little out of date. The second half of video 2 goes on and on about not drawing over other edges. This advice is obsolete for V8. Nevertheless the general advice and explanation of concepts is excellent.