There are many slick daily painters (those that paint and market on ebay a picture every day) in the USA, eg qiang-huang.blogspot.com. Many of them paint foliage brilliantly, using three techniques, bravura brushwork, edges (hard or soft) and crafted light/dark contrasts.
I intended to have a go at these techniques, but wavered from my original intention, simplicity. The results were interesting, but not what I intended, it all got a bit fussy. I'll try again!