Where would I start?

I am 18 and plan on studying to become a doctor. I however plan on doing this next year or next semester (If I can?) Because my family is doing very bad financially right now so I want to work a little.... I also want to really consider what I want to invest my energy into for the future.

I was very good at studying through elementary and Middle school (probably means nothing lol) but fell of bad during high school due to just taking a bad path.

I know its very hard to become a doctor and being a pre med student in general but I know I can do it and it's sparking my interest.

However, I do not know where to start.

I would really love some help!

Also, from experience, what are some things I should consider when choosing to study to become a doctor?