Hello,

Depending on how old you are right now:

• In high school, take whatever science and advanced mathematics classes are offered. (That is, take biology and chemistry, too, not just physics.)
• Go to college, and major in physics. (And graduate!)
• Go to graduate schoool in physics, and earn a Ph.D.
• Apply for and accept one or more postdoctoral fellowships in your field of specialization.

To be an experimental physicist you need to acquire experiences and be open.

On the theoretical aspect you need to be very good at math and understand it.

The former suits more a “scientist of physics”, and obviously you need a degree in order to be credible and gain experience.

Hope this helps....