Before you take any course, consider the purpose. Are you taking the course(s) for:
University credit: Choose a course, in person or online, from a reputable university accredited with a national accreditation board. If you’re taking the course at a different university than the onw where you’re enrolled, make sure your university accepts courses from the other university. Check the offerings at public universities and community colleges as their tuition fees are usually lower than private universities.
Professional continuing education credit: Choose a course, in person or online, but make sure your professional association and/or human resources department recognizes the course and will grants the credit hours.
General interest: Check if your local university or community college lets you audit courses, that is, attend the classes, in person or online, but you don’t do any assignments or exams. You can do them on your own, but the instructor will not mark them. Auditing a course does not give you credit at an educational institution or for professional continuing education, even if it’s offered by a reputable and accredited university or college. Also check your local library. Mine offers a lot of short online courses in many different fields, for free for anyone who holds a library card, which is also free.
Depending on where you live, and the university or college you wish to attend, there may be tuition discounts for senior citizens or veterans.