Set brush opacity to 20-50%, adjust brush size and hardness accordingly, I usually use a small percentage of hardness so that the new color will blend in nicely.
Use eye dropper tool to sample the neighboring color, then just brush over the glares, that’s it!
Just got a hang on engraving using a Newing Hall 350 engraving machine paired with Engravelab, so I tried to engrave a futurama scene onto my ipod nano, here is the result. Should have used a 100 degree diamond drag needle instead of 120, finer lines and details.
Also did engraved a USB cufflink with USB logo
And one more from actual client request, shown with orignal logo and finalized vector graph