We represent other company's products or services. 

So for us, there are two types of leads:

Project Leads - These are potential clients for our firm. If we're successful, we'll get a contract to represent their product or service. 

Customer Prospects - When we get a project from a client, say "Customer" we then go out and try to generate business for that Customer. So for that Customer, we will have a bunch of leads specifically for that customer. 

How do you use Zoho to capture this correctly?

I can see how an Account would be a client for our firm. 

But how should I capture prospects for our Customer/Account?