Grammar JLPT Level N5 - Lesson 19

Like たほうがいい, ないほうがいい is used in Japanese for giving advice. However, this expression suggests that it is better 'not' to do something.
This phrase is constructed by using the negative tense of a verb grouped with 方(ほう), the particle が, and the い-Adjective, いい.

• あそこは危(あぶ)ないから、行(い)かない方(ほう)がいいよ。
  Because that place over there is dangerous, it would be better not to go there.
• それは触(さわ)らない方(ほう)がいい。
  It would be better not to mess with that. (触(さわ)る has the nuance of 'mess around with', whereas 触(ふ)れる is closer to simply 'touch')

As 方(ほう) can be translated closely to 'way', or 'direction', this expression is suggesting that one specific choice is simply the better 'way'.
This expression is quite direct, and can imply that there may be some sort of negative consequence if the (A) verb is done.

• 虫(むし)が入(はい)ってくるから、窓(まど)を開(あ)けない方(ほう)がいいよ。
  Because bugs will come in, it would be better not to open the window. (The negative consequence is that bugs will come inside)