Colorization of a simple black and white photo won't take long. You will need to outline every object you want to colorize with the color you've chosen for it. The vital thing is to choose the right colors for the photo to look natural. You will love the result!
Do not forget to assign a color to the small details, for example, to the stem and the petals of the lilac in the girl's hands. Otherwise, they will be colorized into the color of the adjacent areas, in this case - the color of the dress.
Select colors for the lips, skin and hair from the Color Library.
To paint the dress white we should change the brightness range of the white strokes.
Select the white color from the Color / Swatches palette (or click with the Eyedropper tool on one of the white strokes on the image), then move the black marker on the lower gradient under the Color Library to the right.
Activate the Magic Tube tool and click on any stroke of the dress. Now the strokes have the same color but a new brightness range.