I worked in an office for 30 years and packed it in about 4 years ago to do gardening full time. My only regret was that I did it too late. Had I chosen this path when younger , and more ambitious, I could have built up a pretty good business I reckon. But my advice to you would really depend on how old you are, how experienced you are and how ambitious you are. Since I do not know these things I’ll waffle for a few minutes instead.
I decided to keep things small as it makes for an easier life. No one tells me what to do and I only work for people I want to work for. There are many advantages but don’t overlook the disadvantages of working for yourself. Get some pretty cards printed up with three or four bullet points and drop them in letterboxes. Decide on how much you want to charge but don‘t advertise your hourly rate on your these cards. Can you live on this after you have paid tax, NI, maintenance costs for your van, etc.?? Allow for days when you cannot work for reasons too many to mention. If you are going to be late or cannot make an appointment always phone people up to let them know.
It might be obvious but stay clear of poor neighbourhoods and drop your cards in areas with nice houses. Target small, independently run, housing estates and offices with grounds. A lot of these will already have contracts with gardening firms but they may not be happy with the service and, if you are a one-man band, you will be able to do the work cheaper. These are little gold mines as they will pay you more than Mrs Smith or Mr Jones at 47 Park Drive. Decide how much you know about gardening and, if you can, attend a horticultural college to get a grounding in the basics. Even if you are fairly knowledgeable about plants and soil it will also give you some confidence when dealing with people. Buy decent tools. You’ll need the usual tools but you will also need the less obvious stuff. Take pictures of work you’ve done.
As you have already been doing it for a while all this is probably pretty obvious so I’ll shut up now. Good night and good luck.
Mr pickles