In uncomplicated cases, it is sufficient to excise the scar and reapproximate it with special techniques, such as "extreme eversion".
Typically, special cutting techniques are required to diminish tension on wound edges and to prevent renewed shrinkage (or hypertrophy) of the scar. With big scars, additional measures are often necessary, such as Z- or W-plasties. LINK
In some cases, the appearance of scars can be improved with the application of crèmes, gels, foiles, compression garments, cryotherapy or even with the help of tattoos.