What is the best way to clean my vagina? Vinegar? Iodine?

You don't. Normally you don't need to clean it. The reason is that it is normally populated by acid producing bacteria . They are producing the acid and thus creating environment where pathogenic bacteria do not thrive .When you dush you wash off the good bacteria and the environment they maintain. You can eat yogurt , kefir or take acidophylus culture to support that good bacteria and vaginal health.
Normal bathing. You can use a douche periodically, but you do not want to do it very often. If you use a douche too often, you upset the balance of bacteria and yeast, and encourage malignant strains to colonize you. Normal bathing should be sufficient.