I would say work hard at school so that as many opportunities are available to you as possible. Then I would say find which type of engineering you love. There are so many and all so different that it’s important to read news articles, magazines or research into areas that might interest you. That way you can show your interest. If you can get work experience that would be great. Most of all, if it’s what you want to do then go for it. Don’t let anyone stop you.
Focus on your STEM- related subjects, but don’t forget the other subjects. to be a good engineer or good in any other career you need other skills, such as communication, time-management and etc. If you want to be an engineer doesn’t mean you have to ace the STEM subjects but then not be good for example in English. you need to write many reports you need to present your work to other people, and those skills are essential to help you to be a well-rounded engineer.
Do voluntary works, that can help you to understand STEM better.
Read books, blogs, magazines related to STEM, watch youtube videos about how stuff works, even some basic things.
Try to ask many questions, engineers should always be curious, that helps you to come up with new amazing ideas, and understand how things around you work.
and then just be confident and believe in yourself, work hard and you can achieve anything 🙂