try 1z leather treatment for your seats. You buy it at
www.openroadmotoring.com leaves the leather looking new and not greasy or shiny.
As someone stated already FK1 makes a few great products for regular detailing like 425 as an LSP (last step product) and 1000P high temp wax verrrry durable.
I think the most important thing with a dark colored car is to use the highest quality towels you can afford and wash them after each use. Try
https://986forum.com/forums/poorboysworld.com for waffle weave towels.
p.s.
And try quick washing with
Optimum No Rinse, easier on black paint. Too much soap washing will swirl your paint.