An ex of mine worked in a primary school, and this was his advice:
If you don't mind chemicals, do the WHOLE family in the same evening with nit lotion/shampoo. Three days later, do them all again. Also, wash everyone's sheets and pillowcases on a hot wash, ditto hairbrushes in hot water.
Alternatively, if you do mind it, every day for two weeks, put a LOT of conditioner in your hair when you wash it then use a regular nit comb. Everyone'll need to do this at the same time, otherwise they get passed around from family member to family member. Also, some chemists do a good nit comb with an electric current running through it, so you use that on your hair to kill the lice. You'll need to do that every night for a week.
Hope that helps! Don't worry too much if you do get them - it's an occupational hazard of having a younger sibling.