-Liability Insurance is mandatory. There are two US states where you can avoid liability insurance, but you will still need to prove your ability to cover possible loss caused to others. Anyway, having no liability auto insurance can be the costliest mistake you will ever make and having an accident while driving uninsured (if you are found at fault) may result in years of troubles and loss of your assets.

-Number of uninsured drivers in USA is high, ranging between 1% in Massachusetts and 29% in New Mexico, with national average being 13.8%
If you live in a state with high number of uninsured drivers (like Florida, Alabama, NM, Mississippi, Oklahoma, Tennessee or California) you should seriously consider buying the Uninsured or Underinsured Motorist Insurance.
-Your auto insurance company will ask you about additional drivers using your car. If they are young (typically ones children under 25 holding a drivers license) your premium will increase significantly. If you lend your vehicle to other person, it is your insurance policy that will be affected in case of an accident.
-Collision insurance is important, but make sure it includes the undercarriage, roof, windshield and tires – these car parts are often excluded from the basic coverage. Comprehensive Auto Insurance also covers theft, intentional damage to your car (vandalism), damage by animals, weather etc.