How do I stand out and set myself apart from other applicants?

Good grades, test scores and having extracurriculars are always part of the package. So what is suggested to make yourself stand out is to improve extracurriculars further. This can be through volunteering for certain places as well as getting internships, internships are a good choice whether they are paid or not.

From what I've seen and heard a lot is that colleges favour those who have taken time out of their summer to complete summer programs at different colleges.

The thing that is most likely to be held in high regard is the essay you write, a good thing to do is to look at examples of essays and take time out to make sure yours doesn't sound like you are just repeating your scores, extracurriculars's and grades. What they want is something authentic, something that shows what kind of person you are, they want you to tell a story in a way.

I guess these are some of the most important things that could make you stand out from a crowd of students other than grades and test scores.

I would suggest using the chance tool on College Vine to see how your application as a whole will compare to those of the schools you may be interested in. Colleges review your profile as a whole so focus on building a narrative of yourself throughout the application. From there, in order to help you stand out dive deep into one specific field, you could conduct research, hold an advanced job, start a company, etc. Anything could make you stand out! Also keep in mind you should enjoy the activities you do and not just be doing them for college apps. Diving deep into a subject you enjoy can be done in many ways, but finding a way you enjoy and being able to describe that will definitely help you stand out.

I would suggest reading these articles:

https://blog.collegevine.com/how-to-improve-your-extracurriculars-junior-and-senior-year/

https://blog.collegevine.com/myths-about-high-school-extracurriculars/