Wet your hands and the bar under warm water. Rub the bar between your palms, or against a washcloth, until it builds lather. Apply the lather to your skin in a circular motion, rinse thoroughly, and set the bar on a draining dish to dry between uses. That is the whole of it.
The instruction sounds almost insulting until you remember that a good number of people came of age on body wash and pump bottles. A solid bar is a slightly different object, and the small uncertainties are real: how wet, how much lather, whether to apply the bar to skin directly or work it up in the hands first. None of these are mistakes waiting to happen. They are preferences.
Water first, then patience
Warm water, not hot. Hot water strips the skin and softens the bar faster than necessary, which shortens its life. Warm is enough to release the lather and dissolve the surface of the soap into something that spreads.
Wet both the bar and your hands. A dry bar against dry skin does very little; the lather is where the cleansing happens. Give it a few seconds of friction. Cold-process and well-cured soaps lather more slowly than the detergent-heavy supermarket kind, and the pause is normal. The lather, when it comes, tends to be denser and longer-lived.
Two honest methods
There are two reasonable ways to get soap onto skin, and people defend both with more conviction than the difference deserves.
The first is to rub the bar directly against your body. This deposits more soap per pass and cleans faster. It is the efficient option for anyone in a hurry, and it suits broad areas, chest, back, legs.
The second is to build the lather in your hands first, then apply it. This uses less soap, treats the bar more gently, and gives you more control over where the lather goes. It is the economical choice and slightly kinder to the bar over time.
A washcloth or sponge changes the equation again. The same quantity of soap, worked through cloth, produces more lather and a more aggressive clean through the added friction. Some skin appreciates this; some does not. If yours runs dry or reactive, the bare-hands method is the gentler one.
For skin that needs particular care, healing skin especially, the gentlest version is worth defaulting to. Anyone washing around a new tattoo, for instance, should work the lather up in clean hands and apply it without scrubbing, as set out in How to Wash a New Tattoo, Step by Step. The mildness of the soap matters there too, which is its own subject in What a New Tattoo Asks of Your Soap.
The technique you have is probably fine
Honesty compels the admission that most of these adjustments make no meaningful difference to how clean you get. If you have washed yourself the same way for thirty years, that way works. Skin is not difficult to satisfy. The variations above matter more to the bar’s lifespan and to your soap budget than to your cleanliness.
Where technique does matter is at the edges. Healed skin asks for very little, and after a tattoo has settled the rules relax considerably, as covered in After It Heals, a Tattoo Is Just Skin Again. Until then, restraint is the better instinct.
The one rule that counts
If you remember nothing else: let the bar dry between uses. A bar left sitting in its own pooled water turns soft and dissolves twice as fast. A draining dish, a slatted holder, anything that lets air reach the underside, that single habit does more for a bar’s longevity than any washing technique. Wet it to use it, then let it breathe.