If you have a good grip on the job or profession you'd like to pursue after graduation, I would highly recommend pursuing an internship with a company you'd like to work for. This helps you get the experience you need to be considered for full time employment. While this is a general guideline, there's also a lot to be said about enjoying your time at your age and focusing on your studies. If you feel more ambitious and want to get started early, then look into an internship or part-time job in the field of your choosing. I recommend identifying a list of 10 companies you want to work for and take the first step. Here are some options: 1) peruse the job listings on a job site like LinkedIn, Indeed or Glassdoor; 2) network with like minded peers, friends or college professors; 3) attend a career fair or 4) go directly to the company's website and search for jobs under their career section.
I got my current job through a networking event and my friend got his job by directly contacting the hiring manager even though no job had been advertised. If you feel ready to take the step, try a paid or unpaid internship for 3-6 months and reassess.
As a reference, here's the list of high paying jobs https://www.investopedia.com/personal-finance/top-highest-paying-jobs/ and it's no surprise that healthcare professions are at the top of the list.
I think you need to start looking at what interests you before, and early in, your academic career. Top paying is an interesting question. Pay varies from discipline to discipline, region to region and also based on your qualifications and, initially, your GPA. STEM is generally a good set of disciplines to consider. Also, look at Forbes. They will typically, on an annual basis, have an article or two on areas to live in and opportunities that have high paying salary potential. GlassDoor.com can help you with looking at anonymous salaries.