Such an important step. Quality canvas, brushes, and investing in some textured tools like catalyst wedges make a huge differences. For paints, right now I'm really loving Arteza for metallics, Grumbacher for basics, and Windsor & Newton for specialty colors. Don't tell anyone, but I usually just buy buckets of the cheap stuff when I'm buying white.
This might be my favorite part! You're world building for your little paint community to come explore. I love love a heavy texture paste for lines, mixing sand or gravel with a thick gel for larger areas, or going crazy with crackle paste.
Letting watercolors explore around your texture map is one of the best ways to just let your paint do it's thing. The contrast between the thick lines and sheer washes is divine.
Get Blendy with Acrylic
There's nothing like the a backdrop of creamy acrylics, blended perfectly together to contrast with that thick textures.
Add some Splatter
I love using eye droppers, splashing from my fingers and brushes, or even the occasional cup pour when you need to get serious.
Spray that stuff until your finger needs a protein shake and a towel.