A cheap lead that never picks up the phone is expensive. If this is happening, avoid judging campaigns by cost per lead alone. Follow the whole path instead.
Audience
Is the campaign reaching people with a real need, or anyone likely to tap a button? Broad targeting with a form that fills itself can produce plenty of names and very few buyers.
Offer
A vague promise attracts vague interest. Be specific about what you do, who it is for and, where you can, the starting price. Fewer people may respond, and more of them will be serious.
Landing page
The page should continue the promise made in the ad. Sending people to a general homepage loses that thread.
Speed of follow-up
A lead contacted within minutes is far more likely to answer than one contacted the next day. An automatic WhatsApp acknowledgement and a clear assignment to a salesperson help here.
Measure what matters
Mark each lead as qualified or not in your CRM, and feed that back into your decisions. Then you can optimise for customers rather than form fills.