This is one of my botanical ATCs, a false strawberry (potentilla indica). Medium is watercolors on paper, format is ATC format (6,4x8,9cm). I'm always trying to improve, so... I'd be glad for any helpful advice.
I like the drawing and composition! You've got some very nice detail considering the small size (ATCs are baseball card size, right?) Please consider the following as commentary moreso than criticism:
I think that, as a picture, it works well, but as an accurate picture of false strawberry, it is a little lacking. Your foliage looks almost translucent, and the color of the fruit seems muted relative to the foliage, while in real life this plant has intensely colored fruit and foliage that is somewhat subdued, slightly waxy (and therefore reflective), and unicolored (the veins do not contrast with the blade of the leaf).
So, I think you must decide if you are more interested in a botanical illustration, where accuracy is the primum desideratum, or making a pretty picture based on a particular plant. Of course, both options are equally valid, but I would think that if you are going to draw a relatively obscure weedy plant like false strawberry, you would be more interested in the botanical illustration side of things.