[Perfectlap]

whatever you do don't use detergent or car wash soap.

Rinse the top with a strong spray of water and get an oxo car wash feather tip brush to get out any soap that may be in there from the previous owner.

Then use the Raggtopp like bmusatti suggested. I rinse the car then spray the top with cleanser and work it in well with the oxo brush. Rinse it out thoroughly.
I like to use one of those rubber absorber towels to dry the top and glass, I avoid using it on paint.

Once you use the Raggtopp protectant (stage two) you'll notice that it leaves the top looking a darker more even look. Spray it in coats don't douse the top with it.
The creases may take a few weeks or months to come out. I try to keep my top down as little as possible(only when I'm in the car).