As others have mentioned, gentle and gradual stretching is helpful. Also, giving jaw muscle massages is something for you to try. Obviously everyone has their limits on how far they can drop their jaw, but to reach one's maximum, stretching and massaging are the way to go.Does anyone here have any tips or tricks for improved range of motion in the jaw area? Jaw calisthenics? Jaw stretches?
It was only after coming to TMB and seeing the numbers (and the checking them online too), that I measured myself and discovered why DW had initially had such difficulty in accommodating me. More than my above average length, my girth was more of a problem. Fortunately DW can open her mouth very wide, for longer periods of time now than initially. (I like to joke with her, "Your face is very pretty, but your mouth really sucks!)
We also find that getting the angle right is of help. So, for example, kneeling between my legs while I'm lying on my back isn't very comfortable or relaxing for her jaw. Instead, with me on my back and my knees slightly bent and legs splayed, her lying beside me with her left ear on my stomach allows her to relax and receive me the best. Her right hand can manipulate and direct my shaft while her left hand reaches under my right leg and curls around to hold and stimulate my balls, etc. A well positioned mirror allows both of us maintain eye contact and to watch her do her magic!
On a separate note, there is another benefit of this position for those who have a strong gag reflex. In this position it is possible for her to receive the ejaculate in the pocket of her cheek, if you so choose.