The old third above is good, aye, but not just playing a third above each note of the melody. As long as you've got two of the notes from triad of the chord, or a passing note towards one, preferably avoiding an open fifth, it'll sound great. Especially if you can get the harmony line counterpointing above and also below the main melody. I'm a sucker for suspensions too. *drummer disguise blown* Ahem...I mean, I like heavy sticks...