It is very easy:
1. Switch AF to manual (isn’t necessary to do it first, it can be done anytime before step 5).
2. Go to WB menu (with Fn button);
3. Choose the last option (manual white balance)
4. Point camera at plain white paper sheet (or anything neutral white).
5. Take a picture;
6. Confirm with “OK” button that manual WB is set.
7. Set focussing back to AF.
Don’t be afraid of those 7 steps. I was very specific and everything is done in 5-10 seconds.
Of course you don’t need to do that before each picture, just do it once before photosession (artificial lighting in room won’t change, right?). Very simple and you’ll definately get better WB than any AWB or preset WB. __________________