After getting the sketch onto the watercolor paper, mix up a large puddle of yellow ochre or raw sienna. Paint the whole paper with it, beginning with the top. Keep a bead of paint-water at the painted edge, this will keep you from getting any lines or streaks on the paper when you have to stop to refill your brush. Get darker as you go, till you are fairly dark by the time you have reached the bottom edge of the paper. Remember that dark appears to come forward, while lighter and cooler recedes. This establishes a "mother" color and sets the stage for atmospheric perspective, as well. After it has completely dried, begin your painting. Your lightest lights are yellow instead of the whiteness of the paper and this is what gives this method such a beautiful patina.
The yellow coming through the pink areas gives it a quiet, peaceful tone.
By the time the whole painting is laid down, the eye doesn't sense that there are no real whites and translates the paler, yellow areas as whites. Just quieter whites.
Here, I realized it needed deeper background tones and also where I decided the subject was going to be sitting on a wooden surface. The finishing touches are often, to me, the fun part. They make the whole piece glow.
Notice the yellow in the shadow/reflection area to the right. I cheated, and put a touch of white gouache on the handle. One little white shine to give the glass a hard, smooth appearance.