If your smoker doesn't have a lot of space you might consider buying a rib rack. A rib rack allows you to stack the ribs on their sides so that you can fit more rack on your smoker than if they were laying out.
One tip with putting your rack of ribs on the smoker is to not stretch out the rack. Meat shrinks as it cooks and you don't want to limit that action. Once you place the rack on the smoker push it together gently from the ends. This will let the meat (and fat) contract evenly as it cooks. Stretching out the rack can cause the ribs to be a little tougher once cooked.
If you don't have a smoker you might want to ready my article on cooking Barbecue Ribs on the Grill.
