Use the right size. Your dentist will advise on the right size. Start on the smallest size.
Aim at the triangle space near the gum and poke the stick in. It should come out the other side and can be felt by your tongue.
Imagine your face like a clock face so the piksters start at 12 o'clock, and come around to 3 o'clock when you reach the molars. Access to the molars is 90 degrees different to the incisors.
In areas where there is no room for piksters, use floss instead. See video...
Informative dental care demonstration for periodontal gum care, and also good for nurses in aged care.