There are no real rules when it comes to creating symmetry and balance in paintings. A lot of it is “your eye and gut instincts.” However there are some things that just look awkward. For instance the subject of the painting should never be dead center in the work. The subject also looks out of balance if it is squeezed into a little corner. However there are some mannerist forms of painting, such as naive art, where this type of awkward looking composition is actually desired.
There is one rule that is very important. It is called the Rule of Threes. This means that things in a painting look better grouped in threes rather than twos. This is a standard rule of Japanese painting composition but it is a well known contemporary oil painting technique as well. Basically all you have to remember is that an odd number of subjects or objects in painting look better than an even number.
There is a similar rule in contemporary painting composition known as the Rule of Thirds. This rule dictates that one third of the painting should be devoted to dark space, one third to light space and another third to grey space. However there are some experts that would disagree with and would think that you would do things like vary the negative space in a painting. Another rule is “two thirds, one third, and a little bit.” For example, two thirds dark in tone, one third light in tone, and a small area or object that’s mid-tone would be typical of the type of experimentation that would comprise a modern painting.
If you want the painting to look in proportion you should also prevent objects from barely touching. Composition wise this is known as “kissing. This creates a weak looking shape that is unattractive to the eye.
Yet another rule of composition has to do with color. Do not mix warm and cool tones in the same painting. It is jarring to the eye and looks amateurish.
An important part of getting the composition right in a painting is to do some thumbnail sketches first. Make a map of your composition so you can’t go wrong. This is a plan that helps you get what you want to do in the painting absolutely right.