You will need to start by getting some sort of training in cosmetic procedures. Unless you're derm or plastics, you don't have any experience with this and will need it. So, you go to one of these weekend courses, preferably 2 or 3 of them, to get some training. They run about $4-5K/ course.
Next, you need to create a demand for your services. If you're working in an employed position, you're unlikely to find your employer receptive to you using that to advertise your outside services to your patients. So that means advertising. Print, online, local media, social media. Do some work for free and let people spread the word about you.
You're also going to need an office to do this. Again, your boss isn't going to let you do it at their office, unless you're doing it under their auspices and they're getting a cut. You'll need at least one assistant to do the scheduling, ordering, assisting during procedures. You'll need your own malpractice insurance. Whatever you have through your regular job won't cover this. You could go bare, but that's a recipe for losing your a$$ when (not if) you get sued. You'll also need to find time to do this. Will your regular job be only 3 days a week? Are you going to do this on evenings/weekends?
You're going to have to come up with the capital to buy the supplies you need. Botox, Restylane and all that other crap ain't cheap. I would say that, from a start-up cost perspective, you're looking at high 5 to low 6 figures, assuming you do it right.
You could also find an "aesthetic medicine" office or a Med Spa near you and ask to apprentice with them. Maybe they need more help and would be willing to help train you.
Good luck.
