There is no 'one' right or wrong way to model a head. Everyone seems to have a technique they prefer, but there is a vast number of different ways that a person can choose to tackle the problem of modeling a head in 3-dimentions.
I think that one of the earliest things that I started trying to model was a head, and I can tell you that I made a LOT of very ugly heads. I think that it was the 12th or 13th time that I modeled a head that it actually looked okay. So if this is your first time trying this, and it doesn't come amazing, don't worry. This is one of those things that takes practice to get right.
I've used lots of different techniques to model heads. It seems like I was trying a new technique with every head for a while there. The technique that I'm going to use today is the one that I've used on the last 3 heads I've modeled, and I personally think I've gotten the best results with it.
This is not the only/best way to do this! If you try this, and it doesn't work out for you, don't loose hope, there are plenty of other options to try
Modeling without reference is possible... but in my opinion, it's kind of stupid. Sure, it's possible for someone to model something amazing without using a single bit of reference. But I bet they would have gotten it done quicker, and without having to fix things nearly as often if they'd just taken some time in the beginning to prepare.
Modeling a head without using any reference is probably just a very quick way to get frustrated.
For reference it's usually a good idea to use a photo of a real head. Sure you can draw a head, but it won't be as accurate as a photograph, and will be more likely to mess you up at some point.
But this tutorial is for modeling a stylized head. Something more along the lines of anime. For this I would usually just go off of a drawing, however this time I'm doing something a little different.
Not too long ago, I found a website (http://dreamofdoll.com) and I FELL IN LOVE with the faces of the dolls. The second I saw some of the photos of these dolls, the first thing that came to my mind was "I wanna model that!" So I saved the pictures and they have rested on my hard drive ever since.
When I was asked to make a 3D Anime Head Modeling tutorial, I remembered the pictures and decided that this was a good opportunity to put it to use.
So This is the head I choose to model
Not only is it a straight front shot, it's also got a perfect profile shot. It was perfect reference for modeling. But it still needed some prepping.
There are some important key things to take into account when preparing modeling reference.
1. The images that you put into Max need to be the same size as each other. If one image is 400x412, the other one needs to be 400x412 too. Not only that, but they need to be lined up to each other perfectly. The head needs to be the same size, the noses need to be aligned, the eyes, the chins, the mouths, etc
Take your two images side by side and rotate and scale them until they are the same size and are lined up properly
In Photoshop, turn on rulers by pressing Ctrl+R. Click on the top ruler and drag down to create a horizontal guide line. Click on the left ruller and drag across to make a verticle guide line.
Make your two images so that they're still aligned, etc. These are the final reference images I ended up with
Avoid having a white background on your images! If you draw your reference images and have it on white paper, darken the image in photoshop so that the background is grey. If your photos have white backgrounds, do the same. When you have objects selected in max, that object's wireframe becomes white. If the image you are using as reference has a white background, it will make it very difficult to see the object over it!