Pentatonics are a great way to start playing over progressions. For example if you have a regular diatonic progression like G major, D major, E minor, C major you could use the pentatonic scales that go with those chords. IE G major pentatonic over G major and D major pentatonic over D major. It's kind of like what the other post said about chord tone improvising but you have 2 more notes to choose from in every pentatonic scale over each chord.

You probably won't want to do this all of the time because it can get old and sing songy sounding pretty quickly but it is a great/fun way to start playing over chords.

Nate