And will gladly share what I learn with you, for I have never worked with any of these methodes before.
You should get hand on as many photos as possible, both for painting and sculpting. A good place to start is looking at the Liara Status in the Bioware Store
Photo: Bioware Store
I have a tiny head, giving me the advantage of just using a polysterene head as a base, as to cast a mold of my own head. Then I started to slowly cover the head with clay. You should use oil based clay here, since you do not want the clay to dry out.
So far I mostly used my hands, but for finer details you should use tools. You don have to buy expansive sculpting tools, I have used spoons and other kitchen appliances. But tools do make it easier. Also for the scale pattern I used the netting from fruit and pressed into the clay.
And remebmer, don't let your clay dry out. I have worked with both oil clay and air drying clay. It was way cheaper to use the air drying kind, so I used that. If you need to take a break, spray it with water and wrap it in plastic film.
Sculpting is tedious work, you have to be patient and don't give up. I think I used about 15 hours on my first sculpt. And I have redone it, second time took 7-8 hours I think.
This is my second sculpt.
NOTE: You should not let you clay dry out. This will make it much harder to get out of your plaster mold. Next step - making the plaster mold.