Many people are attracted to the idea of becoming a law enforcement sniper, but it is a very difficult profession, and it takes a considerable amount of skill and dedication. Beyond the great difficulty involved, some people simply aren't cut out to take the job for psychological reasons. You'll need nerves of steel, and you have to be able to take the shot when it's required. Numerous lives can be depending on you at any given time, and the pressure is tremendous. The process of becoming a sniper will vary somewhat from place to place. Different police departments may have their own particular application process, but certain things are usually universal.
First you have to get a job as a police officer. This will typically require passing a police academy program, and in some cases you will need a bachelor's degree as well. Most officers pick criminal justice. You should pick department with a SWAT program because most law enforcement snipers are deployed as part of a SWAT team.
Keep yourself in great shape physically. The training program will require you to be in peak physical condition, so it's best to always maintain that kind of conditioning.
You'll need a strong record as a police officer, and in most situations, you will have to become a SWAT officer before you can even try out for a sniper job. This is not an entry-level position, and you'll have to prove yourself before you even get the chance.
Learn to shoot a rifle with great accuracy. You will have to master it to an extent well beyond a normal level of proficiency. Being familiar with your weapon is a key part of this. You must know it like the back of your hand.
Stick to a single kind of bullet. You'll need to have a precise sense of how it will behave when fired. Maintaining shooting consistent habits is a key part of being an accurate shot, and that starts with being comfortable with the bullets you're firing.
Learn to fire accurately in different weather conditions. You'll need to know exactly how wind and rain will affect your bullet over different distances.
Keep track of every single practice shot you take. Make note of your results in a notebook, including the rifle used and the conditions you are shooting in. This will help you develop the right mental approach needed to be a good sniper. You must regard every shot as absolutely crucial. Each bullet, and what happens to it, is important.
After you've managed become a SWAT officer, you may get the opportunity to apply for a sniper job. If you are accepted, you will have to make it through a very difficult training program. During the training, you will have to prove yourself, but if you make it through, you will be prepared for the job.
Don't despair if you fail. This job is not for everybody, and only a very small number of people have what it takes. Even being a great shot doesn't guarantee you will be up to the task.