Do-It-yourself home paint projects bring a sense of pride and accomplishment to the home owner -- as well as saving the cost of hiring a painter. If you have flat or non-glossy paint and decide later to paint a glossy color instead, you can alter the flat or non-glossy paint and not lose out on the investment in paint that has been made. You will need a few additional supplies from a hardware store but no special equipment.
Pour one part of the non-glossy paint and one part of the glossy paint of the same base and color into an empty paint can. Continue this procedure until the paint can is at least two-thirds filled.
Mix the contents of the paint can -- you can use a wooden paint stick, but a mixing bit attached to an electric drill will blend the two paints together more efficiently. Continue the blending procedure until the paint color is uniform to the eye.
Dip a wooden paint stick in the mixture. Swipe the moistened end of the stick against the wall. If the paint looks glossy to the eye -- meeting your approval for glossy -- you are done; otherwise, add more glossy paint to the mixture in the can and repeat the procedure of stirring and testing the appearance of the paint when applied to the wall.