One thing Emma Jane Lefebvre wanted to emphasize about watercolor materials is to "always work with what's in your budget. To be creative doesn't mean you have the most expensive supplies." The number one thing that you'll buy as a watercolor artist that will make the "biggest difference in your work," as Lefebvre put it, is good quality paper.
If you're working on practice strokes and not a final painting, "working on cheaper paper is completely fine." For a final product, Lefebvre said "I find it best to work on cold pressed 100% cotton watercolor paper and being at least 300gsm 140lbs. Brands like Arches, Canson Heritage, [and] Saunders Waterford paper are all great choices. They are a bit more on the expensive side but are totally worth it." Lefebvre also noted that "finding a good quality paper sketchbook is also a great way to keep all of your paintings together. I love the Etchr cold pressed sketchbooks for that."
Watercolor paper is either rough, hot pressed, or cold pressed. Rough paper is, as you might guess, more textured. Hot pressed paper is very smooth with little texture to it and paint will dry very quickly on it but it's not ideal for a more layered painting, and cold pressed is sort of the goldilocks of the three (depending on the type of painting and effects you want). It has texture but not too much, per The Spruce Crafts.
