Training is one of the most important things you can do as a shooter. It doesn’t matter if you are new to the sport or been shooting for 50 years, there is always something you can learn. Actually if you’ve been shooting 50 years, there are probably a lot of things you can be reminded of! :-)
Training can be reading and then practicing what you read. For most people the most effective way to learn is with an instructor. It can be expensive, so you want to plan your training to get the most benefit. Choose your trainers carefully, read reviews, understand what their style is and what will be covered before you commit. Is the course at the right level for you? A class that addresses the basic fundamentals may be boring for an experienced shooter, and a fast paced, shoot 5000 rounds in a weekend while moving and drawing from concealment could cause a new shooter to go home, sore, frustrated and scared!
It can be good to go back and revisit fundamentals if it has been a long time, but be prepared for the material, and pay attention, even if you think you know it already. There have been a lot of changes over the years and you will probably learn something new or hear it presented in a new way.
If you are an instructor already, consider asking another instructor if you can sit in on one of their classes, and offer them the same courtesy. You can learn a lot just seeing how someone else presents the material.
Remember, train as if your life may depend on it.