The following list contains the resources I use in order to help me make beautiful homebrew content.
GM Binder: Make your own book-authentic homebrew documents, organize all of your documents in one place, discover the works of others.
Watercoloring in GM Binder: By QalarValar.
5e PHB Style Watercolor Brushes: Courtesy of pstutorialsws.deviantart.com
5e PHB Style Watercolor Brushes HD: Courtesy of pstutorialsws.deviantart.com and thedurrrrian.deviantart.com
Full Page Watercolor Stains Guide: By /u/flamableconcrete
Homebrewery Full Page Stains Imgur Album: By /u/flamableconcrete
GM Binder Styling Reference: By /u/Rhaenon