Tip:
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X
All right first load your model and the picture you are gonna use.
press 5 in your numpad to change between Orthographic and Perspective
Choose the view you want and then put the model on almost the same position as in picture
Once you click on project from view move your model around using "G"
To scale your model press "S"
Keep checking in object mode if its correctly mapped check the tricky parts like mouth and nose
Just move the model in the UV area till it fits the most
make sure you color those hard to reach places in the model, the nose sides , eye lids and mouth
to make it fit better when scaling ( Press S) press the mouse wheel button to increase/ decrease width or height
and thats it just fix the small details using those buttons, if you ever need to rotate the model press R I didnt use it on the vid but sometimes
you will have to use it