Make sure you leave the conditioner on to do the nit combing, I usually wrap them in a towel, bring them into the front room, put tv on and then they sit on floor in front of the settee so I can comb, I too do nit combing every Sunday.
Then back into the shower to wash conditioner off hair.
Make sure you wipe the comb on a tissue with every stroke, you can't always see if there is one on there otherwise.
Definately get a nitty gritty comb, they are about £10 but honestly worth it.
The vosene shampoo is tea tree scented and is supposed to deter the headlice as they don't like the smell, supposedly, I'm not convinced, but I think it's just we're willing to try anything isn't it!