I've got a HDS 8 with SS, not G2 tho. I leave mine on auto for SS the majority of the time, right or wrong I dont know but it works pretty good. Other than selecting the palette colors, and figuring out what info you want and how its displayed, learn how to adjust the sensitivity, that seems to clear up or sharpen the view you get more than anything else. There are several tutorials on youtube and written info as well, but the best learning tool is time on the water. Don't plan on fishing much for a while, you'll be pushing buttons and experimenting to see what this does or that does. You will eventually find the settings that suit you. Suggest you print out the manual as the darn thing is a bit complicated and what you learn today, you may forget by the next trip to the lake comes along.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.