Here are three easy keyboard shortcuts that will save you time when applying strokes and fills. First, if you want to quickly switch between fill and stroke and you don't want to bother with clicking them, simply press "x" to toggle between the two. Second, if you want to apply the last-used solid color or gradient to a selected object, press the comma key for the last-used color or the period key for the last-used gradient. Keep in mind that you can always see what these colors are by looking at the icons in the Toolbox. Finally, you can quickly change the fill or stroke color to None by pressing the forward slash key [/]. This changes whichever attribute is currently selected in the Toolbox, so if stroke is active and you want to change the fill to None, press "x" to toggle over before you press [/].