Since Oblivion uses Facegen SDK, means you cannot use static head mesh like Morrowind. You should pick one head mesh(Ren's head meshes are popular, but recently idkrrr's Corean race got popularity. Also check the same author's Saram race. If you want something better than vanilla head mesh, check throttlekitty's
Head06), then tweaking faceshape with Facegen sliders.
Then, make suitable face textures(simply converting other games' is not allowed unless the author permitted it). Stock head, Ren's, idkrrr's use all same UV map, while recent Head06 uses different UV map.
For hairs, you don't need to worry, for Ren already did the job for most of such hairs.