>>2406550then you place the brush outside your selection and use it lightly along the edge of your selection. i can't screenshot my cursor for some reason so i just added this big circle that represents where your brush should go. the result is that whatever you paint with your brush will only appear inside the selection, and since your brush is massive and outside the selection you get this light gradient that ends sharply at the selection. i usually make multiple selections for each part of the body (back, front, breasts, arms) and brush them each on a new layer. you might want to use a lighter or darker colour while brushing depending on the image. once you're done, you can change the blending mode of your layers to something. in this picture i used luminosity, but i think i've used linear burn in other pictures (not this one because this picture was dark to begin with). just try them all and see what works best, sometimes not using a blending mode is better.
