Use RAW, use manual control. Unlike video where you can expect widely varying exposure conditions in a still photo you have plenty of time to figure an exposure. Using the histogram, push the exposure until you are just under the maximum. Look up 'expose to the right' on photography sites for more info. This prevents you from having to push up exposure with concomitant increase in noise.
Try to get as fast a shutter speed as is possible while keeping to reasonable ISO numbers. The Phantom camera is NOT a high ISO queen unlike modern DSLRS. Of course,,the entire rig cost less the a lot of my lenses. Part of this might be moderating your expectations. It's an 'OK' still camera, not a great one. Don't plan on heavy cropping. If you are using Photoshop, take advantage of the supplied lens corrections.
Careful post processing is a must. You cannot do heavy handed adjustments with a Phantom RAW file. It will fall apart into a noisy mess. Subtle sharpening. Subtle noise reduction. The HDR functionality works well.
I find it takes more work to pull out o good image from the drone as compared to my D800. But you can't get that perspective on the ground.