I know it is a little too early to be asking this since I am only a Junior, but after I got my PSAT score, my guidance counselor suggested that I consider applying to Harvard and Yale. I just want to know if I have a shot at getting in, and what I could do to improve my chances.
GPA: 4.75 weighted, almost 4.0 unweighted (all As and one A-)
SAT/ACT: Haven’t taken yet but I got a 1500 on the PSAT
APs: 5s on AP Biology and AP European History, currently taking AP Physics and AP US History, plan on taking more APs next year
Extracurriculars: Altar server at my church, Patrol Leader of my Boy Scout Troop, part time job at a gas station, Key Club, Latin Club, after school homework tutor once a week, National Honor Society, Foreign Language Honor Society
I would probably apply RD.
If you scored 1500 on your SAT and your GPA stayed the same, your objective stat’s put you in contention. Beyond that, no one can say unless you were tell us you are a recruited athlete, your parents/grandparents donated or are about to donate multi millions, or your father is the Prime Minister/President of some country. Just look at the results thread and see how many incredibly talented and high achieving students were deferred.
Your best course of action is to continue to do your best academically and to try to make a difference in something in your community (could be school, neighborhood, city, county). Also start thinking about a variety of schools that match you in terms of interest, geography and cost, including schools that have much greater than single digit acceptance rates like Harvard and Yale. The goal is get to a list of between 6-20 schools by September that you would be happy to attend, with a good mix of safety, match and reach schools. If you have a good state flagship, especially one with a good honors program, try to apply to that as early as you can. Those usually are on rolling admissions, and if you can secure admissions there before the end of December, it should cut your list down significantly.
Are you the President’s son? If not, nothing is sure when it comes to Harvard.
Ask what prompted your guidance counselor to
suggest you consider Harvard.
Was it merely the prestige of the name or was he thinking about a unique program of interest to you?
Read up.
Pick schools - of all caliber - that suit you best: academically, geographically, financially, and any other way.
I would be aware that guidance counselors can sometimes have agendas that have little to do with you, like making the school look good with a Harvard admit 
Your grades and presumed scores would put you in contention but otherwise you can’t have any idea of your chances. Admissions is really about assembling an interesting class with a mix of talents and interests. A side note: elite schools are trying to honor actual jobs (like yours at a gas station) as extracurriculars, so don’t discount the importance of that.
Please make sure to find several schools of varying selectivity where you can be happy, and also look at the finances before you get invested. The Colleges that Change Lives website is a place to start. Also look at the “Little Ivies” (google) like Tufts, Amherst, Williams, Wesleyan etc.
Chances at Harvard are slim for everyone except the groups mentioned above.
You sound like a great kid. Good luck!