May I ask how niche the directory website is?
With selling anything at all, it's about uncovering the need for the exact target market. So are you clear about what the value is to the client? What expensive problem are you solving for them that isn't already covered by local directory listings?
And do they see it as an expensive problem that they're willing to pay to solve?
If it's local retail business that you're targeting, it would be important to test the market with some face-to-face conversations. (In retail, from my experience, 20 minutes is about the maximum time to speak to the business owner, and it's important to get them at the right time of day. For example, a pizza shop owner is likely to have more free time in the morning, but a dry cleaner, in the early afternoon.)
It really comes down to the business problem that you're solving for them, and whether they are ready and willing to pay for that. Testing the waters first can save you from creating a great product with no one wanting to buy it, and I'd hate to see you go through that.
I assume that this is a platform with business on one end and consumers on the other. To be able to make a value network like this work, you should be quite strategic in how you work with sales. The platform doesn't have much value without users, and you therefore need to make sure that the most "picky" customers are the last to enter the platform. In most cases this would be the consumers.
This advice will be most suitable if you have a small or medium sized marketing/sales budget. If you have a big budget (millions of dollars), you will be able to do other sales activities as well.
Advice: You should start with finding the companies. In other words, the part of the network with biggest potential economical upside of using your website. These users are most likely to stick around long enough for the consumers to follow.
The way you should start with this, is through old fashioned door sales and cold calling. And make sure it is as easy as possible for these companies to join, regarding price and use of time. When you have a great amount of companies in one area, you will be able to launch the website for consumers in that specific area. Do not aim to big when you start out. Make a great product for a chosen area, and you can scale from there.
I need to know more about the segment if I'm going to be able to advice you on a step by step guide. Mostly because different segments, especially when it comes to age, respond differently on activities as face 2 face sales, instagram/facebook marketing, influencer marketing etc.
But in general to make a value network work;
1) Make sure the businesses join first.
2) Launch for a specific area, so that the products works great for the first users.
3) Make a marketing plan for getting the consumers "on board".
If you need a more detailed talk on how to get your company up flying, you'll be able to schedule a call with me.