The statement of purpose (SoP) on a tourist visa is vital to being approved. By stating clearly what you intend to enter the country for, what you plan to do there and how you plan to live, you can quickly move through the interview and application process. A clear SoP will also minimize errors due to hazy reasoning or response. The faster your application is processed the shorter your wait time will be.
State in as few sentences as possible what you intend to do in the visited country.
Declare whether you plan on going as a personal visit or whether it is a business trip, at the beginning of the statement.
Refer to the amount of time you plan to stay in the country.
Mention specific places you are going and specific activities that you plan on doing, without adding a lot of details.
Add whether you are traveling with others and if you plan on visiting any friends or relatives while in the country.
Look at this example; "I plan on visiting the United States for three weeks as part of a business trip. I will be bringing my wife and one child with me. While in the United States I plan on visiting my family in Miami, Florida and spending several days at Disneyworld."