I painted these flowers in watercolor, took pictures and sent them to my computer (I was practicing that too, since I am traveling and don't have my own scanner at the moment).

this is the flower I cut out with the pen tool , with some eraser touch ups.

 I added the dark background to check whether it's smooth. 

The next one I just used the eraser. Since I don't have a tablet either, the pen tool will be a great help to me.