How do you use soundtrack in your videos?

[SteriousFilms]

The question is as the title says.
I use it some, but I still don't have it clear on my mind how to use it.
I know it depends on the type of video, I do sketches, for other people it may be different.

 

[epickoshon]

depends of the content in the video.

 

[SteriousFilms]

Yeah, I was asking for some general guidelines you could give.