If the car is new to you but with previous owners then I would suggest getting it back to zero otherwise you’ll never know what others have put on it and what’s making it difficult to clean
Wash it clean with a good car shampoo - Autoglyms or Meguairs
Don’t use a sponge - you’ll scratch it to hell, use a mit with a grit guard in a bucket
Rinse it well with lots of running water (not jet wash)
Dry
Then clay to get all contaminants and previous products off
Then polish - having terrific results with Meguairs Ultimate Polish - it’s much better in my opinion to Autoglyms Resin Polish
Then wax to protect it
Then just use Meguairs waterless wash and wax if it gets dirty or a Detailer if it just a tiny bit dusty
I’m only intending to wash with water once a year unless I go mud plugging
