I'm working on a followup to this, but in short, each mode can represent chord tones, for one thing. Also, you can base a composition primarily in a certain mode. And, for each mode based in the major scale, there are 3 pentatonic shapes you can use that cover the entirety of the mode. But, to start with, try chord tones... ie: the ii chord uses Dorian It's like having a variety seasoning selection at your fingertips. I hope this helps. Keep jamming!