Bumps along the bikini line are usually not a shaving mistake so much as a shaving method problem. A close blade cuts hair below the surface of the skin. When that hair grows back it can catch under the skin instead of breaking through, and the result is the raised red spots most people call razor bumps or ingrown hairs.
Here is what actually reduces them.
Do not stretch the skin
Pulling the skin taut before you shave feels like it gives a closer result, and it does. That is the problem. Releasing the skin lets the cut hair retract below the surface, which is exactly the condition an ingrown hair needs. Shave with the skin relaxed.
Shave less often, not more
Irritated skin needs time. Shaving daily over an area that is already reacting keeps it inflamed, and inflamed skin traps hair more easily. If the bikini line is sore, leave it for two or three days.
Exfoliate on the days you do not shave
A soft washcloth or a mild chemical exfoliant clears the dead skin that sits over the follicle. This is worth more than any post-shave product. Do it between shaves, not immediately after, when the skin is already sensitised.
Go slowly, and stop pressing
Pressing harder does not remove more hair. It removes more skin. Light contact and a slow pass will do more for you than force.
Consider a foil shaver instead of a blade
This is the single change that helps most people. A foil shaver holds a thin perforated screen between the blade and your skin. Hair passes through the perforations and is cut at the surface, but the blade never touches you. Because the cut happens at skin level rather than below it, regrowth is far less likely to become trapped.
It is a trade-off. A foil shave is not quite as close as a fresh blade against stretched skin. For most people, that is a fair price for skipping the bumps. There is a fuller comparison in foil vs rotary shavers, and if you are coming from a blade, what to expect when switching.
If you want to try this approach, the Veloura razor is a foil shaver built for the bikini line, underarms and legs, and it works wet or dry.
Give the area room afterwards
Tight underwear and gym leggings create friction and trap heat against skin that has just been shaved. Loose cotton for a few hours makes a noticeable difference. Skip fragranced products on the area the same day.
What to expect
Changing method will not clear existing ingrown hairs overnight. Those need to grow out on their own, and picking at them is how you get scarring instead. Give any change three or four weeks before you judge it.
If bumps are painful, spreading, or producing pus, that is a matter for a pharmacist or GP rather than a shaving article.
If your skin reacts to most things rather than just to shaving, electric shaving for sensitive skin covers what a change of razor can and cannot fix.