Watercolor painting is versatile and fairly easy to begin learning. The materials can be varied, but for beginners, there are just a few basics that should be sufficient.
Brushes: Sable brushes are the highest quality, but blends of sable or squirrel hair and synthetic will also be fine for starting. Synthetics are lower quality, so if this is your only option, select the highest quality brush you can. You will need a round brush, usually #8, and a flat wash brush, at least ½”. An oval wash or mop brush, usually size 3, is useful for getting large amounts of water and/or paint onto the paper quickly.
Paint: A few higher-quality paints will be more useful than a lot of low-cost colors. Paints are available in student and professional grades and come in tubes or pans. Pans are less expensive, but dry out faster, while tube paints are ideal for covering large areas, and are useful if you paint often. Some artists recommend you start with a warm and cool version of each primary color, which allows for mixing the other colors you need. There are many other color suggestions, but this depends on the individual.
Paper: Watercolor paper comes in rough, hot-press, and cold-press. Rough paper is textured, hot-press is smooth and slick, and cold-press is in-between and slightly textured, and usually best for beginners. Paper comes in sheets or blocks, and sheets must be stretched to minimize rippling and warping.
Other Materials: Most pan watercolors come with a palette. For tube paints you can use any palette, but a covered one will keep your paints from drying out. You may also benefit from a drawing pencil, kneaded eraser, and a few odds and ends such as a spray bottle, sponge, paper towels, and whatever else makes your painting experience the most rewarding.
As you work, you will quickly discover which paints, papers, brushes, and other materials work best for you. The best thing to do for beginning artists is to dive right in, and enjoy the learning process!