We use dimethicone. I buy it in bulk and keep it on hand in case we find a nit during weekly nit checks. Keep in mind you need to leave it (or any other smothering treatment) on for 6 hours to fully suffocate the lice and nits. We usually do it overnight.

Yes to getting the heavy duty comb, not using the ones that come with nit treatment packages. You only need one though, ours has lasted for years. I keep it in the shower so that I can nit comb my own hair if I have ANY reason to think I might have lice.

If school or daycare has lice circulating, I put my DD's hair in French braids and also spray lightly with the Lice Away spray, which is supposed to have some repellant properties. I also spray hats, hoodies, and coat collars with it for good measure. It smells like licorice.

You can hire a lice lady to come show you how to do nit checks and nit combing, but I personally had good experiences just watching YouTube videos. The key is to figure out how to segment your hair properly so you don't miss any sections of scalp. Make sure not to miss behind the ears, the nape of the neck, or the crown of the head, as these are the areas they are most likely to nest.

Whether you hire someone or not, don't plan to depend on a lice lady or clinic every time you might have lice. It's just impractical, and not necessary. We've only had active lice one time, and since then been diligent about prevention. But when we hear about lice cases at school, I will sometimes do a round of treatment for DD and I just in case, because I want to feel certain we don't have it. If you have the stuff on hand at home, this isn't burdensome at all -- you just do the dimethicone overnight and then nit comb in the morning, it's like 20 minutes of active time, and then I can feel reassured we definitely don't have lice.