some that i can think of are
font: bold 20px Verdana, sans-serif /* one line for variant, size, and family */
color: #336 /* short color code */
height: 0 /* no need to specify unit when 0 */
border: 0 /* same effect as border: none but shorter */
background: #ffc /* no need to use background-color if all is wanted is color */
padding: 0; border: 0; margin: 0 /* to show only content but nothing else */
border: 1px dashed #ff0 /* thickness, style, and color */
margin: 0 0.5em /* specify top, bottom, left, right margin */