Way back in August...okay, last week, we looked at creating interest when soloing on modal tunes. Another way to find notes outside the basic scale is to transpose said scale to other keys. Duuuuude!! Um, uhÉlike, what keys? Funny you should ask that. Using D dorian as our key center. One of the usual suspects is up a half step, in this case, Eb (dorian):

Notice that when we shifted to Eb dorian and back to D dorian, a pattern was used to connect the two scales, creating a sense of resolution.

Another option is down a major 3rd (Bb dorian):

In the above example, both transitions between scales featured strong half step resolution. This makes the choice of key sound organized and intentional rather than random.

Both of these choices (Eb dorian and Bb dorian) closely approximate altered dominants, which are the most often used ways to create tension/interest, Duuuuude. In many respects, transposing to any different key will give you some different note choices against the underlying chord/scale. It's just that some choices have more tension/resolution possibilities than others.