meet a white haired woman, preferably not a rabbitgirl (shown here)

bond with them (make sure you dont cause lifelong trauma). string is the most popular form of bonding, as shown here by shirogane takeru (never achieved pravka)

after successful bonding and enough time with your white haired russian woman, you will have achieved pravka. congratulations! if your tsf glows blue, you will know you have succeeded. have fun taking down soldier class, see if you get scouted by the yokohama witch (shown below is a successful pravka user)