In Yiddish, a nice person can be referred to as a "ziseh mensch" (זיסע מענטש), where "ziseh" means sweet or pleasant, and "mensch" means a person of integrity and honor. Another term is "nakhshon" (נאַכשלן), which can imply someone who is kind or considerate. These terms reflect the warmth and appreciation for good character in Yiddish culture.
something nice = epes simpatisch (עפּעס סימפּאַטיש)
The Yiddish translation for smart person is "חכם" (khokhem).
In Yiddish, the word "Nebish" means an awkward person, or nerd.
In Yiddish, a Schlimiel is a person who can't do anythng right; A Schlimazel (or Schlamazel) in Yiddish, is a person who fails at everything and is thought to be very unlucky.
לאנדסמאן - Landsman
It is not a problem
"Alter mensch."
Mentsh is probably your best bet. It means a good, honorable, decent person and can be applied to anyone whether male, female, adult or child.You can also refer to someone as ehrlich, meaning upstanding and honest.
The Yiddish word for a clumsy awkward person is "shlemazel." It is often used to describe someone who is unlucky or accident-prone.
In Yiddish, a good deed is usually referred to with the Hebrew word, "MITS-vah".
mushuganah (as in a crazzy person :P) ~chachi
Yutz n. (Yiddish) -- a vulgar and unappealing person.