Back in my high school years, I used to train competitive programming intensively. However, I made few progress and eventually failed to realize my dream (become a gold medalist in Chinese NOI). I did some self-reflections these days and want to give some suggestions to the new CPers in this community.
Don't compare yourself to others. Please always choose the training method that fits you best. For example, you may find yourself bad at solving constructive problems (like me lol) while some of your peers can solve them easily. That's not the end of the world! The difference between you and them is probably just a fair amount of practice. And, you may have some advantages you did not even realize, too. Remember, everyone's way of success is different. Don't lose confidence!
Don't cheat. When I was in high school, I used to discuss about the problems with others during the contest. I feel deeply ashamed about this even to this day. Keep in mind that rating is just a number and you are here in this community to LEARN something!