Finishing Detail may just do the trick!

_If you have a piece that looks bland and you can't quite put a finger on how to fix it, shade and or line the edges to get a crisp clean look, it's amazing what this can do.   I never consider a piece finished without this step.
You can corner-load a brush with a deeper shade or complimentary shade and create a shaded border to an area, this adds depth.
You can then create a thin to medium wash (thin color with water on a tile) of an appropriate shade (black works fine in many cases) and load a fine liner with this wash and outline as many detail areas as possible. The line must be extremely thin, so it does not stand out. Say you are doing leaves and you used a medium green on the body of the leaf, you would corner load a darker shade of green around the edges and then outline with that same dark green, or even black if desired.
If you would like to see an example of detail lining, look at the deer stein in the Scenic Section of my Photo Gallery Page