There is a lot of ways to attack this goal. Strategies here would also vary based on your available resources.

I would read these two books to dive into first:
1. The Ultimate Sales Machine by Chet Holmes (https://www.amazon.com/Ultimate-Sales-Machine-Turbocharge-Relentless/dp/1591842158)

2. DotCom Secrets by Russell Brunson (https://dotcomsecrets.com/)

With these two books, it will give you a solid foundation and the proper philosophies to attack that first 100 customer goal.

My biggest takeaways to give you a quick recap:
*Know who that dream customer (Avatar, rich persona profiles)
*Locate where they play and hangout
*Build a database of the top 100-300 dream customers which will be your new "Dream 100"
*Create a plan of action to personally reach out to them with a multi-touch campaign that brings them a lot of value and plants the seed of who you are.

Chet Holmes approach is stellar and his business practices are truly timeless. Russel Brunson has a more modern take on many of the same principles which are refreshing.

Happy to help map out what your dream 100 looks like as I have done this for many customers over the years. Best of luck!