For long curly, hard to dry brush/comb hair (tbh, any long hair really)...
Wet comb with nit comb and conditioner in.
Have a jug or bowl of hot soapy water beside you, a dash of tea tree or lavender oil in it won't hurt either.
Hair soaked in cheap conditioner (a good glug of either oil in that also good, be certain your kid isn't allergic first though. Both are toxic to headlice).
Comb through, section by section, after each stroke through, rinse out the comb in the soapy/oily water, so you can see what you caught and get rid, rather than risk putting them back.
They can't run away, the oil kills, the conditioner suffocates and the comb rinse bath gets them off the head and into something they can't escape from before they die.
You need to do it several times to catch any that hatch after the first go, new eggs are hard to get as they're hard up against the scalp and the eggs are smaller than the adult headlice so may escape the comb.
If you/child will be constantly re-exposed to the source of nits then do it every week.
Use a tea tree and lavender hair spritz (you can make your own, just dilute a few drops in water, shake well before use) on finished hair before they go to school (or in my case, meet up with skanky and ill advised boyfriend).
Once I sussed this I stayed nit free whilst i took a stupidly long time to figure out I should dump said skanky boyfriend!