After searching about a hundred sites, I picked a few to link to here.  I couldn't find
any one site that said it all, so look at all of them and get a feel for it.  

Basic recommendations are:

1.  Use soft ties.
2.  Anchor to a frame member or other solid attachment point.
3.  Don't tie off to the handlebars unless you can get right next to the center.
4.  Use a front wheel chock if you have one.  You can get one at
Harbor Freight.
5.  Use a four point arrangement (4 corners)
- four straps in front (the extra two are optional for additional security)
- two in the rear.  Angle them at 45 degrees to the tie down points.
- front straps should pull forward into the chock.  
- I like to pull the rear straps to the rear.
6.  Use quality straps such as
Ancra.  Some folks like cam buckle straps, others like
ratchet straps.
7.  Be careful not to pinch any brake lines or cables.
8.  Don't hook to the engine crash bars or the luggage bars.
9.  Don't compress the suspension more than halfway.
How to tie down a motorcycle for trailering
AMA Chartered Club