A good exercise is to do octaves, fifths, and thirds with a 1,4,2,3 pattern. For example, in the octaves: 8 Low C (1), 8 High C(4), 8 Middle C (2), 8 Middle C (3), and go up a half a step. For fifths: 8 Lower C (1), 8 Upper G (4), 8 Lower G (2), 8 Upper C (3), and go up half a step. For thirds: 8 Lower C (1), 8 Upper E (4), 8 Lower E (2), 8 Upper C (3), and go up half a step. This is what my percussion instructor taught me my freshman year at Lindenwood University.