The more I use gouache, the more I love it.
When I originally taught myself how to paint, it was gouache that I first used as I loved the consistency and how flat I could get the colour to sit on the paper - I was heavily in to celtic knotwork at the time. Moving on to watercolours and leaving it behind, I've only just recently re-discovered how versatile a medium it is, particularly for inclusion in mixed media pieces.
Today at the studio we executed a foxglove painting and I'm not overly thrilled with mine, I definitely need to spend more time observing the shape of a foxglove 'trumpet'. However, we did add a bee in to our pieces and around the room, many people were pleased at how their bee wings came out, just with the simplest touch of gouache. Masking fluid would have been too hard and painting around them or glazing over the top may have been too big a stretch for some abilities so a little gouache and hey presto! a semi-transparent bee wing appears on the surface.
If you haven't ever had a chance to have an experiment with the medium, I urge you to try it out. I use Permanent White for highlights and it is quite versatile when mixed with watercolours or Brusho. Let me know how you get on and you are welcome to email me your paintings, or share them on Facebook. Have Fun!