A website can look good on a large screen and still make life difficult for someone trying to contact you on a phone. Mobile-first means planning for that smaller screen from the beginning.
Make the first screen useful.
Explain the service, the area you cover, and how to contact you. A visitor should not have to wait for an effect or search for the basics.
Design for a thumb.
Use readable text and comfortably sized buttons. Important information should never depend on hovering.
Keep the page light.
Compress images and load decorative features after useful content. Always provide a readable fallback when an effect cannot run.
Check the contact journey.
Open the website on a phone, find a service, and follow the WhatsApp link. Confirm the number before launch.