The most important thing when mounting an outboard to a boat is making sure that the shaft length matches the depth of the boat's transom. The second most important thing is making sure the bolts are well sealed so water doesn't leak into the boat.

Once it's on, a padlock through the clamp handles stops the outboard being stolen or the clamps vibrating loose, as I show in this quick tip.

Bolting an outboard to the transom.