Choose your paint
Watercolors come in cases or small tubes of pigment. When used alone, they are thick and opaque, and do not cover much area. When used in combination with water, they will thin out and become transparent.
You can use a watercolor block that's gummed on all four sides like the top of a writing pad instead of taping your paper down. It's a little more expensive but very convenient for a beginner.
Select brushes
The larger the brush, the broader the stroke. The smaller the brush, the
finer the stroke. Therefore, for covering large areas of canvas with
paint, a bigger brush will get the job done quickly. A smaller brush
will allow you to add detail more easily. For instance, if you are
painting a landscape, you can use a big brush to lay down the base color
for your sky. Then, you can go in with a small brush and add hues of
different colors for clouds, sun rays, sky gradient, or even stars or
birds.
When considering brushes, not only is size important, but material. Most
brushes you will come across and probably use the most are made from
synthetic hair. Take care to rinse the paint out of your brushes when
you are done.
Start painting!
Lay a sheet of heavy paper out on a table. Draw some very simple design on it with LIGHT pencil marks. A square or circle is a good idea. Put a small dab of any color of watercolor onto the white palette plate. Get your brush lightly wet. If there is too much water in the brush, dab it on the towel to soak up the excess, or lightly shake the excess out of the brush. Drop a couple of drops of water - from your paintbrush - onto the dab of watercolor that you have on your palette plate. Don't use too much - just enough to make the watercolor liquid. Dip your brush into the watercolor liquid on your palette, and lift a small amount of color onto your brush. Next, paint this inside the shape drawn on your paper. If the paint is too thick, and stays in one place, dip your brush into the water again and add a little more water to the paint on the paper. Keep experimenting with different amounts of water versus paint mixtures to get a feel for just the right amount of water versus paint you desire. If you want a "dry brush" look, you will use less water on your brush versus the amount of paint. If you want a very wet flowing look, you will want more water versus paint, etc... Fill in the shape with color on your paper. Let the picture dry.
Take a piece of watercolor paper, tape down the edges firmly on a drawing board. Using a big brush or a sponge, get it wet all over. Then try painting into that with different colors. As the paper dries, observe the different ways the paint reacts with how much water there is on the paper.
You can get a very smooth background light color by going wet into wet. Colors mingle with each other on the paper easily and some colors migrate more than others. Try laying down stripes of blue, then a stripe of yellow or gold next to it, then a stripe of red after the gold when it's very wet. You'll see the mixtures your colors create as they form a smooth gradation.
Try letting it dry until the sheen is gone but the paper is still damp. Now your strokes will still be soft edged but a little more defined. Once the color's down, let it dry completely and then add details wet on dry. Use a very simple subject at first that has broad areas of color. Mix some sky blue. Mark some hills and a tree in your sketch lines. First paint them in loosely wet in wet. Then start adding some large details wet on damp. Finally add all the smallest details with wet on dry when it's completely dry.
You can tell when the paper is completely dry because it will no longer feel cool. Hold the back of your hand over the painting, but do not touch it. It takes a little practice to really feel the dampness this way, but touching your painting could damage it or leave skin oils on it. Don't remove the tape around the edges until it's completely flat and dry. The tape is what's keeping the paper flat or flattening it out again when it bubbles up.
Try using a big wash - lots of light color - in an area. Then shake salt in it before it dries. You'll get some beautiful effects that you can use to make snowflakes in the sky or lichen on rocks.
Try drawing on the paper with a white colored pencil, wax crayon or candle end to see the lines show up when you watercolor over them.
Try cutting out shapes in masking tape and painting inside those shapes to get exact shapes. Anything you mask with masking tape will stay clean and white.
Always paint watercolor paintings by painting the dark areas first and paint around the light areas. Paint around or mask anything you need to keep white. Getting used to "negative painting" like this will also help you get more accurate outlines to objects than trying to draw the object itself. Try drawing just the shape of the space around the cup exactly and the shape of the space within the handle instead of drawing the cup. You'll see a big difference in accuracy!
Try "glazing." Once a watercolor mark or area is completely dry, mix a thin wash of another color and paint over it quickly. It will change the color and if you do it carefully, won't disturb the details you painted under it. A light gold glaze on sunlit areas in a landscape can make the sunlight look much richer.
Read books and articles on watercolor and try the ideas in them. Watch videos on YouTube and other places to get ideas for watercolor techniques. Then paint something you really like.
Learn more about watercolor painting process here.
