How to sharpen the edges

Now I'm going to let you in on a little secret of the trade.  Take a look at this leaf I'm pointing to with the pencil:

I need to make the edge of the leaf look as sharp and clear as I possibly can, so the image will jump off the page.  Can you see a faint dark green line which follows the edges around the bottom of the leaf and ends right where I put my pencil?  I take one of my smallest brushes, a size 00, and paint a really fine line using Chromium Oxide Green.  This pigment is a grayish green, and is one of the most opaque watercolor pigments (really cloudy, in other words).  It will hide a multitude of painting transgressions.  Right after I paint the edge, I try to blend the 'leaf' side of the line in with the adjacent green color.  But the outside edge I leave alone.

Now sit back and view this leaf from more of a distance.  Can you tell a difference in bottom half of the leaf, which I have worked on, and the top half (above the pencil) which I still have yet to do?  Isn't that cool?  And from even more of a distance, as you would normally view the painting, it really is effective.  I don't have the steadiest hand in the world, so my edges tend not to be naturally sharp and crisp.  (Does this say something about my personality?)  So when a teacher of mine shared this secret, it transformed my paintings. 

Oh and yes, I will soon put some legs on my ladybug!