One of the best ways to become familiar with chords in all keys is to take a simple progression and transpose it to all of the keys. This may be slow at first, but the more you do it, the easier it gets.
Play each of these common progressions as both chords and arpeggios until you are totally familiar with them, as they occur frequently in songs. Then try improvising over them. The more familiar you are with frequently used progressions, the easier it will be to improvise when playing with others.