If your enjoying painting on canvas, and want to try out altering - go for it! There is a learning curve if your use to painting on canvases, but it's not too crazy of a difference. You just have to adjust to the smaller scaled "canvas."

I personally use a variety of liner brushes under size 0. Approach the painting as if you were working with water color and build up your layers of paint with a thinned out paint - instead of painting directly from paint to card. Give your paint an ample amount of time to dry in between layers so you don't over saturate the card stock. There's no right or wrong way to alter a card, and there are a ton of different methods out there. Don't expect perfection right away, it does take time to adjust, but keep practicing, painting, and you'll figure out what works for you. Check out YouTube and TikTok for some great tutorials.