Cheapest and most beneficial health insurance for an 18 year old female who is healthy?

Varies with area. Health insurance varies by state.Some of the national companies sell products in some states & not others. Decide what you want out of your insurance & look into whats available in your area. Some insurers have an online site that can provide good basic information & you might want to talk with an agent to clarify issues. The more coverage the more expensive but at your age it shouldn't be to bad.