A plan before painting can be helpful as it provides knowledge of your tasks, on the other hand, it inhibits spontaneity of your work.  Allowing the evolution of your painting as you work is free and allows spontaneity of work.  Likewise, it opens the possibility that the painting would have no direction and end up in a mess. 

The degree of a plan depends on the personality and some people consider it important and others a hindrance.  Several decisions have to be considered before beginning to paint. 

1. Decide On a Subject

The decision on the subject is the first important consideration in painting.  The subject determines the support, type of support used, and the technique to use. 
The choice of the subject helps determine the composition and selection of elements without time and materials being wasted. 

2. Decide On the Format

Once the subject has been chosen, the next important decision to make is the format.  The choice of whether or not the format is landscape or portrait or the type of canvass is suited for the subject is critical. 

3. Decide On the Size

Another important decision is the size of the support.  Choosing various sizes will also depend on the sheet of paper or canvass you have.  Deciding on whether the painting would be small or large is an important consideration in the outcome of the painting. 

4. Decide On a Medium and Technique

Using one medium does not totally affect the suitability to a particular subject.  The technique, however, should be critical.  For instance, in using acrylic paint, the decision on whether or not application should be thin or thick needs to be considered too. 

5. Decide On the Type of Support

The type of support affects not only the texture of the finished product but the manner of working as well. 
The technique you chose will also determine the most suitable support you will use. 

6. Decide On Colours

The choice of color is a factor in determining the unity and identity of the painting.  So choosing between using realistic colors or not? Using the colors you have a hand or mixing whatever is on the palette is important.   The range of colors you have within your range is essential in the final output of your painting. 

The plan you make before you start painting sets the tone for the painting itself.  The decision to be made should be carefully done and thought of as it will influence the final output.