We all engage in stereotyping of other people. It is not really possible to avoid this. What is possible is to avoid basing our actions on these stereotypes. In other words, while we are sure to have stereotypes, we can avoid applying those stereotypes when we interact with individuals from a group that we have stereotypes about.
The most important thing that we can do to avoid acting on stereotypes is to be aware that we have them. We have to be completely honest with ourselves. We have to be willing to recognize what stereotypes we hold so that we can effectively combat them.
When we are aware of the stereotypes that we hold, we can act to minimize their importance. For example, imagine a teacher who will be having an interaction with a student that they have not gotten to know personally. The teacher has stereotypes about the student because the student is from a certain ethnic group or because the student dresses a certain way or participates in certain extracurricular activities. The teacher must remind him or herself to treat the student as an individual and to avoid applying stereotypes about the group to the individual.
Although this sounds easy, it is not. Stereotypes are deeply ingrained in us. Therefore, we have to make an effort to be aware of them and then we must make a very concerted effort to work against them.