After Olenka, we meet a Mr. Kukin. Not that he's ever called Mr. Kukin -- his diminutive of choice is Vanichka, and we learn belatedly that his formal name is Ivan Petrovich. (Peter's Ivan.)
Next comes Vasily Andreich Pustovalov, affectionately known as Vasichka. No need for confusion, he's a whole one letter away from Vanichka.
Finally, we meet Vladimir Platonych Smirnin -- Volodochka. Well, maybe confusion is what's intended. All the V's can't be an accident.
Volodochka has a little boy called Sasha. Or sometimes Sashenka. Anyway, the story ends before he's old enough to be called -- let's see -- Aleksandr Vladimirovich. Otherwise, he probably would've been the first of a generation whose diminutives all began with S (Stiva, Seryosha . . .)
It seems you form these diminutives by taking the accented syllable of the first name and adding an ending, preferably with "ka" or "sha" or "chka". It doesn't have to have anything in common with the original name except that one syllable.
Of course, the diminutives are only for use by family and close friends. Most people call each other politely by full first name and patronymic.
If it's too much for you, stick to the stories about soldiers -- they all call each other by their last names.
