You can buy special combs which help with early detection. Remember that it's not just children who can have head lice. You'll be fighting a losing battle if you try to keep your child's head clear while there is an adult in the family who has head lice and who will keep reinfecting the child. You need to check everyone's hair. First of all, don't be embarrassed.
Head lice are nothing to be ashamed of.
Besides anything else, they prefer clean hair. Second, tell people. Tell the school, your family and friends. At least one other person who has been in close contact with your child also has head lice. Everyone's hair needs to be checked.