Good for you.
It is nice to see young folks who are interested in getting into one of the most thankless fields known to man.
First thing, I would suggest you go to college and get a good education in something. Anything. Mechanical engineering is a good one. The reason I say this is because when you find out how bad it can get, you will have something to fall back onto.
Ok, now that I have said this, prepare to spend a lot of money on tools. Talk to a lot of mechanics in your area, get to know them.
Ask them for advice, show them you are interested. Keep your options open.
In a lot of areas, they have apprenticeship programs, check into them and see what is available in your area. Talk to construction or heavy truck companies and see if they need mechanic helpers.
Most places don't care about the work you have done as projects, just your knowledge. Oil change places won't gain you any favors with shops, so concentrate on the shops who can gain you advancement.
Then there is trade schools like these;
They are the leading tech schools in the US.