How do i make shades for a black and white portrait with oil paints, so it doesnt look just gray and pasty.?

The original photo im using is in black and white also and I want the painting to look like the photo.How do i make shades for a black and white portrait with oil paints, so it doesnt look just gray and pasty.?
Adding to Yelena's advice... (BTW, what Yelena has suggested is known as ';premixed value strings'; and ';preparing a palette'; aka working with a prepared pallet.) When you lay down a brushstroke, do it deliberately and in no more than two passes. This means:





1. Think about the stroke and do not just brush away like you are just being expressive. When you need to actually depict form you have to calculate each move. Painting is an intellectual process.





2. Load your brush with the appropriate value (shade) of gray.





3. Lay the paint down onto the surface with a deliberate stroke of the brush matching what you previously thought about.





4. Stop. Examine the stroke. Usually a stroke needs at least one additional stroke to touch it up or to perfect it. Do not spread it around like you are spreading butter on bread. A brushstroke is like a sequin or fish scale. Think of a fence, A brushstroke is like one slat (panel). Keep your strokes clean and do not overwork them by smooshing them all around.





5. Load more paint on your brush and lay down an adjacent stroke that perfects the first.





6. When you lay down the next fresh stroke, carefully place it next to the previous stroke. When you blend, do it carefully with a deliberate motion in as few strokes as possible. This will vary depending on the effect but the general idea is that you do not want to overwork the paint. Your color and values will be clean by following this general idea.





All of this can take place in split seconds of thought. I do not mean to describe the process of painting as such a slow tiny step by tiny step process, however, I do mean to emphasize that painting is a carefully though out process and every step should be deliberate. Be alert and think about what you are doing. Do not go unconsciously physical like you are playing with a puppy. You do not want to get carried away with the sensation of stroking paint. Get any of that out of your system using house paint and repainting a room or something.





In summary, choose the appropriate value (shade), load the brush, try to lay down your stroke in one carefully considered pass, do not smoosh the stroke around, keep your strokes, colors, and values clean by working with them as if they are each separate, do not do not do not smoosh.....that is a fantasy version of what painting is. Remember, painting is a premeditated activity.





And no running around the studio like a ballet dancer making dramatic sweeps, swaths or any movements on the canvas with the brush resembling a sword fight.How do i make shades for a black and white portrait with oil paints, so it doesnt look just gray and pasty.?
Try mixing an array of shades before you actually start your painting, so you have a big selection when you actually paint. Make sure to have plenty of white paint, and not too much black paint (obviously black paint goes a long way..)