Here when I started residential it seemed like when I pulled up to a curb all the locals pulled out mowers and the whole neighborhood is mowing. I spent some time walking and waving neighbors down to introduce myself. Tuck in the shirt and take off your hat when you meet someone. Talk to every neighbor you can. I was occasionally asked to do small tasks like edge a sidewalk or clean gutters was a real common one. Don't approach as a salesman, approach as a nice guy who like to shake hands. It works wonders being your own word of mouth. The neighbors can see you do top notch work, and they want to know who you are.
I try to gauge how hard it is for my competition to find out who I am because they will try harder than Joe A. Customer to figure you out. If it's really easy for the competition it will be easy for your customers. It hasn't taken me to the big league level, but it finds work.
Don't EVER walk onto a non customer's yard. Always smile and wave from the sidewalk and if you are invited to go further... you get my drift.
Lawn services is the easiest small business to startup, unless you want to do at-home daycare.
Purchase some market research. Amazing what those folks can tell you.