Best way to get started in entrepreneurship and business?

That is good advice and I would echo the just get started advice. You're going to make mistakes and figure things out, so don't be afraid of that; embrace it! Your first business probably won't be your last one, just like very few people marry the first person they ever go out on a date with.

If you start any business, you're always going to be in "Sales" in some manner. You're either selling your idea, service or product, so just expect that you'll be engaged in sales for a while. Don't let that intimidate you because sales is simply telling a story and communicating the value of what it is you're offering to the intended audience. A question you'll hear a lot in business as you pitch ideas is "What pain or problem are you solving?"

This ties into the other piece of startup advice is do something where you feel good about the problem you're solving. Solving a problem can be something small like making an everyday task easier or a better way to use something we already use every day, or it can be something larger.

As you launch, keep trying and don't be afraid to pivot or in some cases to start over; you'll only know of something works by trying. Also, keep asking questions of your intended customers and of mentors.

Once you think you've found the product / service and the audienece, FOCUS! It's easy to get distracted, especially by others with a thousand ideas. Don't tune them all out, but keep your focus and trust your gut.

Glad to hear you say that you are looking to "add value to the quality of people's lives." Do you have a business idea or are you looking for inspiration? To be an entrepreneur, you need to have passion about what you are doing and you need to solve a problem. Take time to understand your target audience and their needs - this is key. As a high school student, there are many ways to further your education in entrepreneurship, and social entrepreneurship (businesses for solving the world's biggest problems). Here are few recommendations about where to start:

Join or start a DECA club at your school
http://www.deca.org/

Check out MetoWe http://www.metowe.com/ and
Free the Children http://www.freethechildren.com/

I personally think doing speech and debate or journalism are great foundations for entrepreneurs. Stay on the cutting edge of technology - try 3d printing if you can or take interesting classes to spark innovative ideas through community college or attending meetups, conferences, etc.

Get an internship with a startup - you can learn massive amounts by just being around a startup.
https://angel.co/jobs#find/f!%7B%22types%22%3A%5B%22internship%22%5D%7D
Even if they don't have a job opening, you can offer to do competitive landscape research or help summarize what people are saying about an issue on social media...

Avail yourself of free awesome online tools - do this now!
IDEO human centered design kit:
https://www.ideo.com/by-ideo/human-centered-design-toolkit
Business plan templates:
http://www.teachingkidsbusiness.com/business-plan-templates.htm
http://www.bplans.com/sample_business_plans.php

Take classes:
IDEO human centered design kit and classes: http://www.ideou.com/ (costs money)
https://www.ideo.com/by-ideo/human-centered-design-toolkit
Coursera
https://www.coursera.org/learn/innovative-ideas
Khan Academy videos...
https://www.khanacademy.org/economics-finance-domain/entrepreneurship2/interviews-entrepreneurs

Get hands on and build or join a team to solve a problem:
IDEO Challenge https://challenges.openideo.com/challenge
HeroX Challenge https://herox.com/

Enter innovation or entrepreneurship competitions to vet your business plan, get mentoring, and maybe startup funds
Technovation http://technovationchallenge.org/
Biz Plan Competitions list http://www.bizplancompetitions.com/competitions/

Look ahead to colleges with great programs...
Skoll Centre at Oxford http://www.sbs.ox.ac.uk/faculty-research/skoll
CASE at Duke https://centers.fuqua.duke.edu/case/

or not college ... Draper University for gap year... http://www.draperuniversity.com/

Since you are still in high school, you can support your choir, you're marching band, your sports team, or some other group by doing a fundraiser.

When I was 16, I held a dance at my high school that raised money for UNICEF during Halloween. I got some of the best guys in town to put together a special band, we charged $5.00 at the door (it was 1972)! And we made $500.

The best part, besides doing something for somebody else, is that this is a project with a beginning, a middle, and an end. You get in, you get out. You're done. See?

The dance/fund-raiser is your product. You're the "owner" who "hires" a team to:
1.) Organize
2.) Promote
3.) Sell tickets
4.) Act as the liaison with the charity you pick (or school group)

It's not some long-term project that has the potential to become a real hassle.

Just "wet your toes," and see if you like the business experience, and then take it from there.

Good Luck!