Everyone and their mother does entry-level clinical work these days, whether it be EMT, CNA, ED tech, phlebotomist, scribe, etc... It's best to focus on your studies and get the highest grades possible. Clinical jobs, unlike volunteering, require a significant time commitment. If this time commitment ends up biting into your study time and your stats tank, then you'll be in trouble. If you have a poor GPA and MCAT, then entry-level clinical work which is commonly seen by ADCOMs will not help you.
Now I realize that some people want to make money, but the money you earn from these jobs is ultimately pocket change compared to future earnings. Also, if you do manage to screw the pooch on your grades and MCAT. You might need to take an additional year off (one year of potentially lost earnings) or do an SMP which will cost tens of thousands of dollars. The chump change you'd make is not worth it.
What you should do is volunteering. Volunteering is a minimal commitment, and will give you what you need to get into medical school. Now I realize people will say that you can do so much more in an entry-level clinical job that goes way beyond what you'd get out of volunteering, but look at it this way, you have the rest of your life to be a doctor and experience all of these great things (on a much grander level).
If I were you, I would stick to doing your best in school/prepping for the MCAT, volunteering, and enjoying the best years of your life before embarking on the life-changing experience of medical school. You won't likely have time to enjoy life once you start medical school, so enjoy it now. If you want a job or need to make money, do something non-clinical. It may be more unique, and service jobs like waiting or food delivery can make you more money with a minimal commitment. I did pizza delivery in college (once a week or two times max, it never conflicted with schoolwork), and had fun stuff to talk about in job interviews (I'm a non-trad), and with medical school.
Good luck!