As best as you can know what type of dental care you or your family needs before buying a dental plan.
One last point about buying dental insurance is to make sure to think not only of your current dental needs, but your future dental care needs. If you have children try to get a dental plan that offer some coverages for orthodontic care if braces are ever needed in the future.
Think about your over all healthcare issues that may effect your dental care needs. If you are a diabetic the gum care is very important and buying a dental plan that offer affordable deep cleanings will be very useful to you in maintain good gum health care. Read, Ask and Know about the dental plan you may buy for yourself or your family. The better you understand the dental insurance plan and what it offers the better you can fit your dental care needs to your budget.