The more I paint in watercolours the more I realise the rules aren't set in stone ...there are ways to break them and create your own .
I was talking to a group last week and explaining some techniques , "oh my goodness", said one woman "I'd be too scared to do that.". But never be too scared, it is just paint, water and paper , whatever you do you can always have another go. That said I know what she meant, if a painting goes well and you don't want to risk, it just keep it and experiment on a new piece.
However as I have painted more I have become more bold. Watercolour is a tricky beast but you can correct mistakes. I have been known to paint one thing, step back and think no that's awful the shove the paper under the tap washing away the offending bee, flower, eye, bird or.tree forever
I have painted darker things on top of areas I really don't like and blurred whole backgrounds that I feel have gone too far or look wrong. I use white acrylic to add a bit of light sometimes and I use masking fluid in large amounts when I think the painting needs it.
My newest hare was not going well so under the tap it went and I added and washed away colour until I was happy . I like to create blooms in watercolour ( you know the cauliflower effects many try to avoid) but in the right place I think they have a true beauty. I stand back from a painting kitchen roll in hand rubbing away parts that are too bold or dark so the areas I want to be the focus stay as the focus.I flood an area with water and flick and splash my paint around
In my opinion it is all art and the more you can let go of rules the better the piece can be.