Create a WhatsApp Group
Create a Group on WhatsApp to promote your products or services.Configure Group Admin only
Then set it up so that only you as the group admin can send messages to it.See the video below to configure it.
This better than a WhatsApp Broadcast list because it allows a person to exit (unsubscribe) the group if they are no longer interested in receiving your messages.
Since no one else can post messages on the group, they can use the “Reply privately” feature on WhatsApp so that replies come to you only.
Invite Friends
Invite your friends on WhatsApp to join them using the WhatsApp group link. That way they have the choice to opt-in or not.
You can even use this to invite people from your FaceBook, LinkedIn and email contacts
When they tap the link they will automatically be able to join the group.
Offer Something
Finally, offer something in this group once a week.
Posting a message every day might be too much unless you’re offering free iPhones. :)