Everyone at my service boards a pt. a little differently, but all methods accomplish the same task.
We all use plastic boards with pins, quick-clips, and coated foam head blocks.
The way that I like to board someone assuming they have no additional injury (hip fx, shoulder dislocation, etc.) is to cross two straps over the chest (like an "X" as someone mentioned earlier), put one across the hips, and one across the lower legs. However, I have recently learned a new strapping technique specifically for carrying down the stairs/inclines and what not. Not many people I talk with seem to know about it, so I figured I'd share.
This method uses five sets of quick-clips along with the C- spine/head stuff
-As far as C - spine/head blocks and what not goes, its the same as usual.
-Cross two straps over the chest (X)
-Put one set of quick-clips on a single pin, on each side of the hip line. make sure the "button" part of the buckle is on the outermost side of the pin. Take the "clip" part and pass it through the void behind the knee. Snug it up to your pt.'s crotch, buckle, tighten, all that stuff. Same for the other side.
-Last clip goes across pt.'s lower legs. Ta Da!
The whole purpose of this particular technique is to keep your pt. situated on the board the way you put them there. We put another student on the board the "regular" way, and carried him down the stairs. By the time we got to the last step, he'd moved down about 4 or 5 inches. He also said he "felt" it in his head when we asked him - obviously because thats going to be the only part that isnt going anywhere using the "regular" method. When you use the "going down stairs" (or the parachute method, as we call it at my service) the pt. wont move. If they do, it will be minimal. VERY minimal (we did the same test for this method.) We came up with this by applying the same concept of a rock climbing harness. Sounds dumb, but it works, and in the end, its more comfortable for the pt.
Now that Im done ranting like an idiot, Im going to call it good and leave it at that.
Take care and stay safe -emsgirl911