I found a wonderful extension for Photoshop that turns all selection tools into handy drawing tools, by automatically filling your selection with your foreground color, gradient or random color.
You can change feather and opacity of your selection among other cool features. It totally changed the way I work on our Childrens Book Roadrunner Rikke right now.

Developer of this plugin is Sergey Kritskiy who also developed a bunch of other very useful plugins for PS and Blender.

There is also a great documentary with videos, that you can check out: Lasso Draw Documentary