I found some great videos on tips and techniques of using masking fluid. I have used masking fluid in some of my paintings and found it very useful.
The Complete Guide to Masking Fluid for Watercolours is a lengthy video but well worth the time.
I have also included two videos by Cheap Joes MaskingTechniques and Tips with Linda Baker and More Masking Techniques and Tips withLinda Baker. These are shorter but still helpful.
I used masking fluid when I was working on this painting back in 2008 - original post,