Here's a useful tip I picked up from a Barry Greene book.
The diminished (whole/half) scale is usually viewed as a series of consecutive whole steps and half steps:
A diminished whole/half scale = A, B, C, D, Eb, F, Gb, Ab
Playing the diminished scale in this manner usually yields mechanical patterns and sequential licks.
If we look closely at the first 4 notes of the A diminished scale we'll notice that they spell out the first 4 notes of an A minor scale, namely A, B, C, D.
The next 4 notes, Eb, F, Gb, Ab spell out the first 4 notes of an Eb minor scale.
Using Barry Greene's concept, a diminished (whole/half) is made up of 2 partial minor scales a b5 apart! Which should make for more melodic lines when playing diminished ideas.
Note #1: The whole/half diminished scale is used to improvise over diminished chords.
Note #2: Over dominant 7th chords resolving to a 4th above, eg. G7 to C, play the half/whole diminished scale. Or use the Barry Greene concept and play your partial minor scales a half step higher than the dominant chord you're playing over. Eg. for G7 think Abm/Dm partial scales.
Pretty useful stuff.