Hey /sci/ I am deciding to major in physics. Any advice?

I haven't started yet, I am going to apply to college soon.
here is the thing, in high school i was a complete idiot and it has been a year since i have graduated . in those 12 months i have changed, i am not longer that idiot but sadly my smartness is still bad. i always loved the universe and nature, plus math bc i always thought the long equations looked so cool.

can you give me advice on how to get smarter and how to prepare myself for physics? what am i going to expect. i really appreciate it.