The finished surface of an acrylic painting is often accused of appearing “flat” or even “dead.” But applying many layers of paint can contribute to the illusion of depth, especially if they’re mixed with additives such as gloss varnish and/or marble dust. For example, try adding a lot of water to create a color that’s more transparent and results in a lighter-gauge film with a longer drying time. Give gel medium a try to beef up the paint body, cause the hue to be more transparent and shorten the drying time. Or try mixing in some acrylic medium, either matte or gloss. Gloss medium will make the paint more transparent than matte and give the paint surface a little sheen.