IT services is a very broad term. You need to be more specific about what you are able to do and deliver. Once you can clearly express what you do and what value you deliver, then just go and door knock local small businesses.

I'm not surprised online adverts don't work. My inbox gets a couple of unsolicited offers to do IT work every week. If I needed IT work done, which I don't, I would reach out to my professional network and not take chances with random strangers on the internet.