I actually made this as a reference piece for elsewhere, but I think people here can benefit from this too.
Please take this with a grain of salt, as I haven't actually consulted any references while doing this; it's just a recollection of all the stuff I know about drawing male faces that I've "researched" on, some of which are purely observations and conjecture, and may not be factually true as it pertains to human anatomy.
And because I feel like a scientist about this, this reference sheet is copyleft. You are free to correct it, edit it, upload it, distribute it, etc. provided everyone else is free to do so to your edited version.
Please refer to the red lines in the images for the following notes.
Draw the shape of the skull as a circle. Please note that this is only the top half of the skull; it has a jawline as well. If you are not drawing the head from the front, the circle is slightly elongated. Skulls are not shaped like perfect spheres. They are flattened on the sides, and very slightly tapered towards the front.
Necklines are typically drawn just in line with the jaw. This only applies to average men. Leave some space between the back of the head and the ear in 3/4 and side views.
Do not place the ear too high. It should be somewhere between the corner of the jaw and the eye. Distortions in perspective may change this positioning, but it typically remains stationary for head tilts since it is closest to the pivot of the angle.
The mouth should be on the same level as the corner of the jawline. This doesn't mean that whenever you take a ruler to it, it will always line up. It just means it's on the same perspective. The mouth also curves according to the perspective you view it from. It should not extend any farther than under the center of each eye.
Most of the features should stay on the same level when you turn the head. Normally, distortions due to distance would make these irrelevant, but in this case, because they're not that far away, they become insignificant.
If any of this sounds weird, unimportant or too subtle, just try it anyways. I thought most of this stuff was weird at first too, and I didn't think it caused problems for my art, but sometimes, less is more.
...And feel free to ignore the last head. That's just me being silly.