Alternatively, start with a limited palette of Burnt Sienna, Ultramarine Blue, and Titanium White. This gives you warm and cool tones while also allowing you to create a full range of values.
You could also buy a starter set which generally includes a limited palette of the three primary colors plus Titanium White, green, and an earth color such as Yellow Ochre. From a few colors, you can make an endless array of hues. You can add to this basic color palette in time as you progress and want to try different colors.
Watercolor or Gouache: As with acrylic, start with a limited palette. Ultramarine Blue, Burnt Sienna, and white (whether Chinese White or the white of the paper) will give you the ability to focus on capturing the values in your composition. Once you conquer that you can expand your color palette.
One of the nice things about acrylics is that you can paint on many different surfaces. Primed canvas panels are great because they are already primed, they are rigid and therefore easy to rest on an easel or your lap if need be, they are light-weight, and not too expensive. For an acid-free archival board try Ampersand Claybord. Other inexpensive options are paper on a board or pad, cardboard, wood, or masonite. And of course, there is always the traditional stretched canvas. The paint goes on more smoothly if you also prime these with gesso first, but it is not necessary with acrylic.
For watercolor or gouache, there are different weights and textures of watercolor paper. Buy individual sheets or get a pad, or block, which is easy to carry around. You can also try Ampersand Claybord or Watercolor Board.
Brushes come in different sizes and shapes. Brushes are sized by number but vary by manufacturer. Buy a brush with synthetic bristles about an inch wide. Often this is a #12. Then choose two smaller sizes. You could also buy a less expensive starter pack to see what sizes and shapes of brushes you like. Ultimately, though, money spent on good brushes is well worth it since they tend to keep their shape better and not to shed as you're using them, leaving unwanted hairs in your painting.
Generally, you want to start out with your bigger brushes and save your smaller brushes for detail.
Brushes for watercolor are softer for a more fluid paint. Try a starter set to experiment with different brushes. A good #8 round red sable watercolor brush is very useful. Otherwise, buy the best synthetic brushes you can afford. A #4 round for detail, a flat 2" brush for washes, and an angled flat should get you off to a good start.
You just need a few more things: containers for water (i.e., large yogurt containers), rags, and paper towel for wiping and drying your brushes, a spray bottle to keep your acrylic paints from drying out, paper plates or disposable palette paper on which to lay out and mix your colors, a plastic palette knife to mix acrylic colors, tape or bulldog clips to secure your paper to a board, and an easel or table for support.
You're ready to start painting!
It is a good idea to look for a teacher in your area and enroll for a course in painting and drawing. Art is something that is possible to learn and you will have the chance to explore different media to use, like a pencil, ink and charcoal. Once you get a feel of this, you can decide to use the one you are comfortable with.
In your art class you will probably begin to draw or sketch objects or live models. Some people prefer painting classes where the importance of color, texture, line and form is emphasized. Most people tend to come up with their own special style of drawing and painting while some stick to the traditional landscapes.
It is okay to stumble during the learning process and end up using the eraser a lot. But as you practice and become better, you will be proud to produce that masterpiece that will take up a pride of place in your living room.