If you are starting from nothing: an unscented wash and a dedicated toy cleaner. Those two cover the everyday hygiene that most complaints in this category trace back to, and neither one takes any learning.
If you are getting irritated and cannot work out why: drop everything scented first. Fragrance, flavor, warming and tingling are the usual culprits, and removing them costs nothing.
If a doctor or pelvic floor PT sent you here: buy the graduated set, not a single size. Progression is the method, and stopping to reorder halfway through is how people lose the habit.
If you own silicone toys: a dedicated cleaner, and never a silicone lubricant on a silicone toy. Silicone bonds to silicone and degrades the surface, which is how a good toy turns tacky and porous.
On materials generally: non porous only, which means medical grade silicone, glass or stainless steel. Porous materials cannot be fully sanitized, whatever you clean them with.