Its so hard for me to stay in the lines let alone keep things simple. However subtlety is something I'm working on in my art. Not so much the slap your face with this is different, rather stops you for a second to go "huh!?" while you ponder what you are looking at trying to figure out what got your attention.
So...I took some Black and White negatives from a shoot the other day and hand colored them quite subtly. Well, kept it to simple elements rather than an entire frame. I think "LOS" was a bit more successful than the wild flowers.