If I don't draw consistently for a long time, my construction understanding seemingly deteriorates. I usually read Hampton for a little bit, but does anyone have any good references or tuts for overall construction... or faces in general?
I'm sure I'll get back to spend just grinding out skulls and shit for awhile, but in the mean time.
Study from multiple different people and combine whatever methods work best for you. Study Loomis but also watch Vilppu and Steve Huston's NMA videos on head construction, and whoever else you like.
The most important thing is that you practice it. Draw a fuckton of heads from imagination, do a bunch of boxes in perspective and carve the head shapes / place the features in them. Don't just read a bunch of shit, try to have fun with your exercises.