I sometimes look at "Audio Library – No Copyright Music" on YouTube and I also use Soundcloud. With Soundcloud you can do a normal search for music, then on the left click "Tracks" then "Filter Results" and change "To Listen To" to "To Use Commercially", pick the song you like and remember to read their description and do what it says i.e. add name and link to song and also add Creative Commons link.
They have different playlists of different styles of music.
I have created some videos on YouTube and have recently started to use these.
You can check my videos on YouTube/marcWbass
Hope that helps.