1) Use a lot of the Characteristic Pitch in your chord progression! In this case the C.P. is natural 6. This pitch can be used as the Root, 3rd, or 5th of diatonic chords. This C.P. approach is effective for highlighting the sound of any Mode and in this case creates the Dorian Mode sound.
2) Be careful with the Tri-Tone. Basically, don't create one. The pitches may be used where this is found, but not together. If used together, the Dorian Mode (or any other Mode) will be lost.
Here's an example - In C Dorian, the C.P. is A. In this Mode, A would be the Root of the vi dim chord. Not a good choice here because of the Tri-Tone. We'll find with other Modes, this Root idea will work. A is the Maj 3rd of F Maj (IV) and is a good choice. A is the 5th of D min (ii) and is another good choice. These chords are referred to as cadence chords and can be used to set up this C Dorian sound. You can apply this logic to any of the Modes to bring out their unique qualities and write Modal music.
Lastly, write a melody that uses a lot of the Mode's C.P. You must use all of the notes of a Mode for it to sound like the desired Mode.
Good luck!