Mapping Elevations and Overlap

I've booked a job that covers much of a hillside. The elevation difference from the highest point to the lowest is around 100'. I'm using a P3 pro (for now) and I'd like to deliver the best accuracy and resolution possible. Should I select an altitude that's relatively low over the higher elevations so as not to fly excessively high over the lower elevations? Current practice has me take a picture on the ground and include it with the upload. Would landing and taking a picture at a few different points on the ground increase the elevation accuracy? This technology seems to be really growing quickly and demand seems high, hopefully I can perform many more of these surveys. Thanks for your help!