Another useful group of words that I learned are used to describe the position of something.
Here are the most common:
上 (Shàng) is up or on
下 (Xià) is below or under
前 (Qián) is in front
后 (Hòu) is behind
旁 (Páng) is beside
里 (Lǐ) is in (like inside)
外 (Wài) is out (like outside)
右 (Yòu) is right
左 (Zuǒ) is left
Often these words are used with either 边 (Biān) or 面 (Miàn) to indicate the position. Both seem to be able to be used interchangeably, but I know most of my Taiwanese friends seem to use 面 (Miàn) most of the time, except they seem to always use 边 (Biān) for left and right.
You'll often hear these after a noun, to indicate a position, in relation to the noun. So
房子后面 (Fángzi hòumiàn) will be "rear of the house".
镜子前面 (Jìngzi qiánmiàn) is "in front of the mirror".