I;d second the advice to go and work for someone else first.
Long hours of standing or bending or contorting yourself into awful shapes.
Most of the available courses will teach you how to clip a dog short in a variety of ways but they won't teach you much about how those breeds should be clipped, or why, and thats because most clients don't want their dogs to look like they breed they are and most clients won't groom between visits to you.. they will leave the dog until its matted and then expect you to fix it.
Ideally you'd be a force free, fear free groomer, which means getting clients in from when a pup is tiny and working hard to ensure grooming is not force based, dogs are happy and relaxed.. but this requires some decent knowledge of dog behaviour and client commitment, and the latter part is the bit you will find really hard.
Most groomers end up forcing dogs to behave because to do enough dogs in a day to make the job pay, you haven't the time to train the dog (which the owner should have done and shoud pay for your time in doing, but they don't).
This time pressure means many dogs are unhappy, uncomfortable and that progresses to growly and bitey
The financial outlay for setting up by yourself is pretty huge, clippers come in at several hundred quid for a decent set and you'll want several, blades 30-50 per set and that the cheap stuff. Blaster dryers, directional dryers, dog bathing systems, grooming tables, suitable venue or mobile van... you are looking at thousands to set up on top of training costs.
Then when you get set up your first clients will be the ones who have been through every groomer in town and been sent away with a flea in their ear over deeply matted dogs, bitey unhappy dogs etc etc. Whilst you are trying to set up your niche, fear free, superduper lovely business with dogs coming out looking like fashion stars, what you are GETTING is clients who want a dog shaved bald so they can leave it six months, or a client who wants a dog that looks like a fashion star but has to be shaved bald as the coat is so bad....
To get the clients you actualy want, you will need skills, and some seriously good marketing, it would help if you are already known within the dog world for your own dogs excellent grooming, for example if you already own and show poodles, that would help.
Realistically to make money you need a decent venue that is low overhead (a double garage converted perhaps) and several people working for you.
If you adore dogs and LOVE grooming (I adore dogs, I love grooming my own, I could not be arsed grooming other peoples) it can be great, but it can be absolute HELL.