The idea is that you never hold yourself in high regard when you refer to yourself when speaking to others. Watashi is a general word so it's okay. However in rare occurrences some women do use "watakushi" or "atashi" (the usual examples are in animation) but the former are generally for people that sound arrogant about themselves.
watashi / boku WA sukottolandojin desu watashi if youre female boku or ore if your male
Watashi no (for a girl) Boku no (for a boy)
Boku (For boys) Watashi (For girls)
watashi/atashi/boku (male)/ no kiichigo.
You may say 'watashi/boku ha ... [insert what you are here] desu.'
Watashi/boku/ore WA ichigo ga suki or something like that. By the way, 'watashi WA' is used for girls most of the time, but not necessary. 'Boku WA' and 'ore WA' is used for boys/guys.
There are several forms, and even more if you venture into non-standard dialects. However, three forms that one learns early on are 'watakushi,' 'watashi,' and 'boku.' 'Watakushi' is a formal expression for "I." 'Watashi' is one for everyday use. It is polite and appropriate in nearly all cases, but is a touch feminine. Thus, guys can typically use 'boku' instead of 'watashi.'
If your a girl it would be 私も (watashi mo) If your a boy its 僕も (boku mo)
私の watashi no (for females) 僕の boku no (for males) 俺の ore no (arrogantly)
It's the male version of watashi. It means 'I'. Both versions can be used by males, but never say boku if you are a female.
Watashi no kokoro 私の心 (female) Boku no kokoro 僕の心 (male)
In colloquial Japanese 'boku' means 'I', so this sentence it would mean, "I don't like you". However for 'boku' to be combined with 'suki ja nai' i.e. I don't like, is odd. It would read, 'Watashi' another personal pronoun for 'I' in Japanese.