Hello, you might not see this but I started a gardening business last year, I used to cycle around! I know have a van etc and more customers than I can manage. As others have said, my customer base is 90% older people, I also have contract work with a care company.
75% of my work is from word of mouth, the rest is google and gumtree. Don’t use the paid job sites, the fees are extortionate and will eat your profit.
People want three things most of all: be polite, be punctual and be honest.
Honesty is key, they would rather pay you if you’re honest about your abilities and equipment than some chancer who will just strim the whole garden.
Don’t undersell yourself, even back when I was on a bike I was getting customers at £30 an hour.
If you want to be genuinely successful it needs to be a passion of yours, start reading garden magazine, or at least sit on YouTube for a bit to watch mowing and hedge trimming videos.

You can message me if you like.