I’ve grown to love the unpredictability of watercolors, watering them down to allow for happy accidents, or opting for more of a dry brush for greater control. I find that Daniel Smith Watercolors are great for embracing granulating colors while QoR Modern Watercolors excel with vivid hues. Some other brands I enjoy include Winsor & Newton, Rembrandt, and occasionally Kuretake Gansai Tambi Watercolors for a Japanese approach to watercolors.
In regards to watercolor paper, I found out the hard way that trying to save money in this department just leads to frustration. With low-quality paper, watercolor pigments don’t respond as well and the paper is more prone to puddling and pilling. I often opt for Arches paper either on a block or stretched myself. For a handy little sketchbook that happens to be 100% cotton, I enjoy Hahnemühle (perfect to pair with my travel watercolor set I keep in an Altoid’s tin)
I’m a fan of how versatile a quill can be with brushes. I’m not currently partial to any particular brand, but some of the ones I enjoy (and weren’t purchased as a gift for me from Japan) are the Da Vinci Casaneo Synthetic Squirrel Brush and the Oriental Art Supply PRE Orchid Bamboo Brush.