The best rules of thumb, or general guidelines, depend on the exact topic. For example, the best rule of thumb for cleaning is often considered to be to clean from the top down. A good rule of thumb is based on common sense and tips that have been found successful when doing a certain task. The top to bottom cleaning rule is based on the fact that if the floor is cleaned before a higher surface such as a table, it can become dirty again from debris falling from above. Rules of thumb can be applied to any industry or task.

The process of job hunting has many rules of thumb known to be successful. For instance, maintaining comfortable eye contact with a prospective employer is said to be an important rule of thumb during a job interview. Other well-known rules of thumb for job interviews are having questions prepared, offering a firm handshake and never being late. These basics are often considered the best rules of thumb for getting hired from a job interview.

In general, the best rules of thumb consist of tried and true methods of doing something. People have different ways of doing things and still achieving success, but a proven rule of thumb usually brings success to just about every person who tries it. For instance, in sewing, one of the best rules of thumb is to always think carefully before cutting fabric. This rule of thumb works for everyone since once you cut fabric, it can't be easily added on again, so stopping and thinking before cutting can work for each person.

The best rules of thumb help stop big mistakes. They advise against what a person's instinct or emotions alone may tell them when instincts or an emotion shouldn't be applied to a task. For instance, driving a car should be about defensive operation to prevent accidents. Studies have shown that many drivers experience the instinct to speed up in foggy conditions. Yet, the best rule of thumb when driving in fog is to slow down since visibility is severely limited.

A rule of thumb often becomes common knowledge if it's a popular way of doing something. For instance, the idea of inserting a straw or toothpick into the center of a baked cake to see if it's done is one of the best well-known rules of thumb because it works very well. Other good rules of thumb when baking cakes are to use the center rack in the oven and frost the cake only after it's completely cooled.