I think another tendency is I would have the Master busy doing *boring* things while the Padawan and friends go on a mission. Sneaking around flipping some switches while the 'PCs' do the exciting rescue in ANH is a great example. Maybe the Jedi has to go and mediate a land dispute, and sends his Padawan and friends to explore around the old ruins to see if they find anything interesting, or scout the area to see what exactly is going on. Your biggest danger is that the NPC overshadows the PCs. I'd use 'Here, you go fight a couple of droids while I battle General Grievous' very sparingly if at all.
I was thinking of a similar campaign, though I'd open the game with Order 66. Basically the Master gets ambushed by the clones, and rather than call his lightsaber to himself or knock the clones away, he uses his last couple of moments to send a vision to his Padawans, warning them of the Clones' treachery. This lets the PCs be ready for them, and has the Master sacrificing himself for the PCs. I was even thinking of having the old master be a former pupil of Qui-Gon Jinn (before Obi-Wan), who had recently taught him the secret of being a Force Ghost. That way the master can still be in the story, but can't directly aid the group.