Hi A,

This is a good question and tricky to answer as we don't always use the same equivalent word as in English.

For the example you quote you just wouldn't say visage.

You might use 'visage' to describe a particular trait of a person's face like -

Elle a un beau visage, un visage souriant, un visage sans rides, etc.

or for specifically talking about the front part of your head -

J'utilise un savon moussant pour me nettoyer le visage = I use a foaming soap to clean my face 

and there are some expressions using visage like -

Faire bon visage = To put on a brave face

But 'tête' is used in a different way to English often too like in -

Se laver la tête = To wash your hair

Faire la tête = To sulk 

etc. 

So it's just a case of knowing which the French use but not easy I know.

Hope this helps!