Quite a frequent question from aspiring entrepreneurs. To which I have only one answer: "There's no fucking way. Do it somehow. What didn't work - change it. What worked, improve it. That's business. Nobody knows in advance what's right or what's best. To find out, you have to try it first."
Much more painful is the fact that behind such a question usually lies a lack of understanding of how to do it at all. The "how best to reach clients" question is decoded as "I have no idea how to find my clients or how to reach their attention at all." But that's a bummer. And we do not cure bugs.
Take programmers, for example. Nobody makes the tenth version of a program at once. It's the same in business. First make the startup version 1.0 - as you know and as you know how. If it will be used, then you yourself will see and learn how to make the second version better.