How to prepare the vagina for sex? Well I’ve heard it all now. It is not like it has a mind of its own. It is you that prepares for the moment---not the vagina. However if I have misunderstood the meaning of the question, and what is meant by it, for instance, smartening it up with a pubic hair trim, giving it a thorough clean or adding a touch of sweetness (fragranced products) which I suggest you don’t do, then this makes sense.
Freshness is paramount regardless. You’re dealing with a delicate place and therefore select feminine products carefully. Stick with natural types to avoid unintentional damage.
Despite the fact the vagina is a self-cleaning organ it needs help on the outside to remove odour and gunge sorts. It is not necessary to scrub and neither use strong scented soap as this can disrupt the pH level which is acidic with a pH between 3.5 and 4.5. Upset this and infection (yeast) is likely.
Stick with warm water for cleaning and men will love you all the more for it. The odour you might feel uncomfortable about and have the urge to be rid of is one that turns men on. Take that away and you may have killed the moment for him.
If vaginal discharge comes heavy as the same with menstrual blood by all means turn to soap but one not fragranced. As for douching forget it, that is unless a doctor says otherwise.
Cleaning solutions
Outcomes may differ from woman to woman! (Listings below are not medically proven)
Lemon leaves consist of a compound named limonene. Because limonene is an antibiotic and an anti-allergic agent it supposedly works effectively by bringing freshness, along with having the ability to clean also, plus, helping to maintain the pH. Another is Apple cider vinegar, couple of drops mixed with water of the same amount and left for approximately 10 minutes supposedly protects the acidic state of the vaginal wall. Chamomile oil is known to work well with odour as the same goes for baking soda.