Find an old eyeshadow (or buy a cheap one) in the form of either loose or compacted powder, rather than a gel form. Scoop the eyeshadow into a bowl and use the back of a spoon to mash it up until you've got a fine, lump-free powder.
To give the lipstick some shimmer, try adding a little shimmering eyeshadow to the main color you have chosen. Using eyeshadow is a great way to experiment with interesting lipstick colors. Eyeshadows are like color pigments so that's why we use it. Go for green, blue, black, and other colors that are difficult to find in lipstick shades. Note that some eyeshadows are not safe for use on your lips, however. Check the ingredients. If the eyeshadow includes ultramarines, ferric ferrocyanide, and/or chromium oxides, do not use it. Only use eyeshadows that contain safe iron oxides.