But I'm not sure what skills to use or what to role play. I know conjuration would fit, but what else?

Depends on what you mean by witch: game's version, the stereotypical Halloween version, Wicca, etc.

The TES version. I'm playing as an evil witch too.

This sounds like a decent build. Maybe there are some things in it that will help you.

http://theskyrimblog.ning.com/group/character-building/forum/topics/character-build-the-volkihar-banshee

I made this almost exact thread a while back, never stuck with my witch though. I actually used an orc, which is perhaps counter intuitive but I was envisioning the bent nosed green witches you occassionally would see in children's books. Plus I just like orcs. I think I will try it again in a future tes with better character creation.

I was half basing mine on childrens books and half on real world voodoo witches from primitive tribal cultures in sub saharan africa and melanesia.
So sometimes black robes to slink around in civilised places and other times forsworn armour to be out in the wilderness performing dark rituals and worshipping nature like a pagan outcast.

Emphasis on alchemy and conjuration (only zombie raising), enchanting and had decent one handed just to nod to her primitive savage side (which is admittedly not befitting the archetypal euro witch). I'd sneak into villages and kill chickens, kind of wished she could kill children because that would be quite witchy, but what can you do?

She was also a cannibal.

I'd think a classic witch could probably utilise all schools of magic.

Here is another one.

http://theskyrimblog.ning.com/group/character-building/forum/topics/character-build-the-witch

Is she made of wood?

Has she got a wart?

Will she turn me into a newt?

Thank you so much, Ashley, I didn't know about this site. It seems really interesting and inforamative.

It is a very interesting site. It has given many on these threads a lot of ideas. Hope you find some good ones.

It's...