I see many dangers in your sentence "Help businesses post their services to reach customers".
To significantly increase your chances of success (and avoid extreme overwork which often causes burnout), I highly suggest you do two things :
1 - select a specific industry
2 - select a specific geographic area
The best parallel I can do is with Starbucks. It looks today as if they are everywhere. But in reality, they started small, tested and tuned their 'system' locally, and gradually expanded geographically.
Facebook did the same (started by only focusing on the academic market, with a clear focus on the 'dating' aspect, and then expanded).
In your case for example, your statement could be "Help accountants in Boston post their services for free to reach a larger consumer base".
Notice how you get instant focus with this simple change, you now know who to reach on both ends.
You can get even more focus by using a specific business size and smaller geographic area :
"Help accountants doing over 5M$/year in Cambridge post their services for free to reach a larger consumer base".
I clear message like this is very important in terms of customer acquisition because this level of specificity creates an 'this is for me' reaction, which instantaneously creates trust in your solution (one size fits all is dead).