Quick vacuum to first to remove abrasive dust. Normal day-to-day car shampoo is fine washed off with a hose - do not use a power washer as this can damage the waterproof rubberised central layer (advice from a soft top fitter/expert). The Autoglym proofer is quite good although you need to remove any overspray from paintwork and glass before it dries. I've also used Fabsil Gold (painted on not the aerosol) which works well although it smells slightly strange until it fully dries after around 24 hours.
Human shampoo sounds fine and is guaranteed to be gentle. I have also seem Milton's Baby sterilising fluid recommended to prevent green algae.
Many "human" potions make very good car care products. Dove soap and warm water does a great job at cleaning leather seats followed by E45 cream (the small tubes of actual cream) left overnight - recommended by an old Aston Martin worker. No need for expensive "car care" products
