A good way to get a new student bassoonist to appreciate the fact that different lip pressures should be applied to the reed from the lowest to the highest register on a bassoon, is to have them blow just on the reed producing the lowest note possible with loose lips then try to produce the next four higher notes of a major scale (up and down a few times) by progressively tightening the lips.
Right from the beginning the lungs should be filled with as much air as possible and air pressure maximised relative to lip pressure. In forming an embouchure the upper lip should be further forward on the reed than the lower lip in a natural overbite. To demonstrate a nice rounded embouchure, have the students pucker their lips very round and forward of the teeth, then place a finger in their mouth and squeeze the finger with the lips only while visualising the lips tightening around the finger like a drawstring bag.
While the lips are around the finger, push the lips gently backwards against the teeth so upper and lower lips comfortably cover the teeth. This is a good natural embouchure but it must be appreciated that almost everyone’s embouchure will look slightly different because of facial characteristics.