I second the larger canvas! Tiny canvases mean you need different tools since your area of coverage is drastically different, meaning the 2" brush will be too big. If you want to save money - I'd recommend getting canvas paper, they come in different sizes!

[Experience from painting a 5" x 7" seascape after painting on the 18" x 24"]

If you are getting mud - I'd recommend not loading the brush as much as you think you need. The point is to get some color on the canvas and then later blend. When I was following one of Bob's paintings - he really emphasized scraping off excess paint exactly because the "thin" paint sticks to "thick" paint.