The first name is the most common form of address between persons who enjoy a close relationship. The use of the various forms of the first name (similar to our American nicknames) is influenced by the degree of intimacy in the relationship. The greater the intimacy, the more variety in these forms. For example:
Full forms of the first name (Влади́мир, Татья́на)are the most neutral forms of address between individuals who are on either Вы or ты terms.
Shortened forms without suffixes (Воло́дя,Та́ня) indicate a certain degree of closeness. These forms are often used interchangeably with those in category A and are appropriate when the relationship is either Вы or ты.
Nicknames with the suffix -ка (Воло́дька, Та́нька) imply intimacy which may be without affection. The younger generation prefers these very informal forms and depending on the situation, they could also be interpreted as condescending.
Only if the individuals are on ты terms should the "diminutive" or"affectionate" forms of the name be used. Nicknames with these suffixes, -ечка, -енька, -юша,-юшка (Воло́дечка, Воло́денька,Та́нечка, Таню́ша) have a very specific coloring and non-native speakers of Russian will want to take care in using them. Russian women seem to favor the use of diminutive forms more than men and as you might suspect, men will use diminutive forms when addressing women, but not when addressing other men.
Nicknames with a "zero" ending (Воло́дь, Тань) belong almost exclusively to the younger generation and non-native speakers should avoid them. They are used as a type of vocative case, that is, when trying to get someone's attention.