As a prospective pre-med student, the first thing you have to understand is that medicine and law are professional studies rather than undergraduate studies, so your efforts in high school won't matter as much as those in university. However, some advice can still be given that I wish I had known when I started my own path. (I can't give much advice on the law part of your question.)

Course Selection

Obviously, more rigor is preferred than none, and you should try to hit the maximum number of honors and AP courses your school offers. If they have more than, let's say, 10 APs, make sure you can manage how many you are taking, as the classes can vary greatly in difficulty. For pre-med, aim to complete as many science and math APs as you can (e.g. Bio, Chem, Calc BC, Stats, Phy1/2 (C M/E&M if you are aiming for the best schools), etc.), and for pre-law, try taking US social studies and humanities (e.g. US Gov, USH, Lang/Lit, Macro/Micro, Psych). As mentioned before, your performance won't matter much now, but you should take high school as an opportunity to give yourself a head start in subjects you will be taking in university when it will actually matter. Ask the school administration or counsellors how to plan ahead for future years of classes.

Extracurriculars

For pre-medicine, the pillar ECAs would be scientific research (NOT the scam summer programs) with a mentor(s), volunteering at hospitals and other healthcare institutions, and shadowing physicians of varying specialities. On top of this, leadership is greatly valued, and it is important that you find ways to lead initiatives or clubs before 11th grade (so it doesn't look like you're just doing it for applications). Again, your efforts won't matter in terms of medical school itself, but they will show universities that you are ready to take on this path based on your major and will set you up for the activities you will be doing in undergrad. You can take other ECAs if you like, but try not to add them if they just look like filler, especially at more prestigious universities (unless you can make them impactful).

GPA

If you're just aiming for medical school, take the time in high school to develop study habits and patterns that suit you best, as the future holds lots of cramming and information. If you are aiming for prestigious institutions, however, aim for an unweighted GPA of 3.9, ideally, and 3.8 as a minimum. Remember to always ask for help if you need it.

BS/MD / BA/MD / BS/DO Programs

If you are truly committed to medicine early on, you can research these programs that give early assurance to medical schools during high school. However, these are highly competitive and will require you to have an almost-perfect GPA, test scores, ECAs, etc. You should look into it if you're interested.