The simplest solution is to have a professional conduct head check, but if you want to screen at home, it’s important to get the right tools. You will need a proper professional lice comb, available at Lice Clinics of America. Low-quality pharmacy combs have poor tines that lack the strength, spacing, or grooves to promote friction necessary for lice removal.
Fill a small white plastic container with water. Comb through the hair from root to tip, and then aggressively rinse the comb in the water. Make sure you are scraping along the scalp with each pass. With proper lighting and magnification, examine any dark floating items to see if you have removed eggs or bugs. Eggs have a teardrop shape, and bugs will look jagged due to their legs and antenna.
Lice and eggs can be VERY small, so when in doubt, schedule an appointment with a professional.