You'll attract the maximum number of customers when you offer a benefit they cannot get from your competitors. If you don't already have a USP, create one by adding something to your business you're not already offering. Convert it into a benefit statement and include that statement in all your advertising. Offer free information related to your product or service to generate inquiries or website traffic. You need a system to collect contact information enabling you to reach them again with periodic reminders and offers.
Advertising is expensive.
Maximize your return on it by following up periodically with the prospects it produced to convert more of them into customers. They don't want to take the chance of getting something different than they expect and maybe even losing money. You can eliminate this risk by guaranteeing satisfaction. If you sell products, offer a liberal money back guarantee. If you provide a service, offer to continue working without additional charge until the promised result is achieved.