The primary settings I adjust throughout the fishing day include:

SI sensitivity. I typically start in the 10-12 range. If fishing hard bottom areas (sand, gravel, rock) then I dial down the sensitivity. Soft bottom (muck, mud, etc) calls for higher sensitivity.
SI contrast. I usually range from 8-14. I dial in the sensitivity first and then fiddle with contrast to make details stand out.
SI sharpness. Normally off, but when I see a few fish tight to the bottom, I set sharpness to low or medium to help them stand out better. Here's an article I wrote last fall that details this procedure:

Using Humminbird Side Imaging's "Sharpness" feature to find bottom-oriented fish

SI range. Normally 100 ft, but I'll dial this down towards 80 when examining objects for fine detail.
Chart speed. 1-2 for trolling, 2-4 for searching at idle, 5-6 for low speed and 10 for full throttle.

Hope that helps!