Most important advice (and you can see it repeated here) is that you need to be used to rejection. An average developer might get never get a PR fully rejected -- a well oiled sales team expects to close only 1/3rd of their sales qualified leads. If you're starting from cold calls, you will be lucky to close <1% of your outreach, prepare for that mentally.
But also (again repeated in other comments) you aren't selling a tool, you're looking for their problems, try to understand them in their words and then show how giving you money makes them go away (it doesn't have to all be solved with software, your skills in setting up the system can be just as valuable).
Happy to talk more if you aren't comfortable discussing in a public forum: dave@demogorilla.com (we make software to make remote SaaS demos better: https://www.demogorilla.com)
But also (again repeated in other comments) you aren't selling a tool, you're looking for their problems, try to understand them in their words and then show how giving you money makes them go away (it doesn't have to all be solved with software, your skills in setting up the system can be just as valuable).
Happy to talk more if you aren't comfortable discussing in a public forum: dave@demogorilla.com (we make software to make remote SaaS demos better: https://www.demogorilla.com)