Words Commonly Not Translated in Scans and Words to Know

Baka- idiot
Aho- Moron
Hai- yes
Iie- no
Arigatou- Thank you
Kuso- damn (or equivalents of damn)
Kedo- but
Demo- but
Moshi- Maybe
Kokoro- heart
Neko- Cat
Inu- Dog

Words added to the backs of other words/names to indicate position
-chan (affection. usually for little girls, or girly things. can also be used for older girls, just not women. may be distorted as -tan, replacing the ch with a t.)
-kun (indication of respect, but not to a superior.)
-san (aquaitences would use this, if they are on the same social class. i.e., a classmate)
-sama (adding sama to someone's name would indicate respect, and that they are high up than you.)
-sensei (meaning teacher, or doctor. not always used at the end of name/words)

Then, the terms stated above (minus sensei) can be added to these:
onee  big sister
oni  big brother
oba  aunt
oji  uncle
obaa  grandma/old lady
ojii  grandpa/old man

they can also be added to the end of names, like:
sakura-chan
tsubasa-kun
kaname-sama
mari-san

Common Sound effects-
Cat sound- nyaa
Frog sound- kero
Mouse sound- chuu
Crow- kaa
Rooster- kokekokko
Pig- buu
Horse- hihiin
Dog- Wan Wan