You may want to only allow customers who you've vetted and approved to earn points with your program. By default, all customers will be able to earn points. If you'd like to lock your program down to only those customers you've approved, you can do the following.
Go to "Settings > Account Settings > Advanced Settings > VIP Multiplier" and set the Default VIP Multiplier to 0.00.
This will make it so that every new customer who signs up will automatically have their VIP multiplier set to zero and earn zero points for any action. They would be inactive, not count toward your plan totals, and not gain any additional points in the future.
For customers who you would like to participate in the program, you can go to "Members" and search for them. Once on their member profile page, you can set their VIP Multiplier to 1.
Note: This method will not work if you want to award customers sign up points. Sign up points will have to manually awarded to the customer when you enable them.