I have heard people say they get the best deals from private owners!!?

I am a 35 yr old woman who has worked hard and saved my little bit of pennies I dont want to get taken for a ride!!! I have about 4000 saved I want to buy a car from private owner,but there are no warranties and i dont want a lemon,how can I make sure all paperwork is aunthentic,or that they are trying to sell a stolen car or something,do I bring the mechanic or will the seller let me take the car to a mechanic.I need step by step help!!!!!!