I discovered the Molotow Masking Fluid Pen after reading about it on iHanna's blog. I couldn't find it in too many American stores, but I did find it at Art Primo online. This pen works just like regular masking fluid, but it comes out from a pen so it's much easier to control.
First, I drew the word "Imagine" using the masking fluid pen. The fluid comes out blue, as you can see in the next picture. After I drew my words, I used watercolor paint to doodle on top of the letters and around them.