Best thing I found out was to find a matching hair for your model. If you use a hair on your model that is close to someones actual hair, they will look similar to each other.
And for the pictures you might need to align them in gimp. Facegen likes to have pictures that have eyes on same level. And sometimes you have to manually tweak them, they may lose their noses depth or have enormous jawline.
And one good way is to tween them with modify on Facegen. Facegen takes two models and tweens them as much as you like. Try it and find out yourself.
Frontal photos are pretty much all you need, unless you manage to find photos from exactly same photoshoot.
Hope this helps.