Freshman in HS

Talk to his guidance counselor

Yep first step is a meeting with the guidance counselor. Usually now they have what they call "tracks" and you have to make sure whatever track your son needs to be on he is on. Theyll ask does he wants community college? University? Etc. Then they come up with a plan and courses he needs to fulfill that track and give him the best odds.
Also important is volunteer work. It is great on a college application. If he is involved with church that is a good place to get any letters of recommendations. Sports and clubs in school is also great on a college application.

Is he taking any honors classes? He is too young to take AP classes. I think you have to be a junior and definitely a senior. He should be involved in school and community activities. He should do a sport or 2. See if he can double up on some of his classes. Take a course during summer. In his senior year, if he finished all his requirements to graduate high school have him take classes at the local community college, something that will transfer. Where does he want to go and what does he want to major in?

Obviously he needs the grades and SAT scores to get in. You can check with the colleges he's looking at and it will give you an idea of what he needs to shoot for in terms of that. Also important is extracurricular activities - sports, clubs, part time job, etc. Some colleges also require certain courses - like 2/3 years of a foreign language or a certain level of math, make sure you check with the individual schools to make sure he is taking what's needed.

Here, you can start taking AP classes as a freshman if you have the aptitude for it

My plan is to enroll my children in college level courses as soon as I feel that they would be able to pass. DH and I were both enrolled at least part time in college by the time we were in 9th or 10th grade, and the school paid for us to go because we had completed our graduation requirements for high school. See if there is a dual enrollment program. We homeschool, so we will be paying for this ourselves, but we are also freer to choose what courses they take.

A wide range of school sponsored activities: one sport, one service, one fun
volunteer work
Great grades! Universities are moving away from looking at weighted grades; this means that an AP A is worth the same as a regular A; that said, universities want students who work hard, and challenge themselves.