There used to be a website on this subject which had all sorts of suggestions including banana skins!!.
I use my wife's clothes, or should I say her knickers and any nice silky skirts or slips she might have. I often use a mirror to have a sort of an upskirt. Besides that I look at a bit of prn on the internet but a lot of it is too OTT or hardcore..........
Any good kinky ideas out there??