I suggest you initially just put it in auto and drive it. Don't over-complicate things to begin with. Let it decide what gear to select. It's what it was built to do.The only time you need to touch the gear lever is to select neutral when say stuck at lights, as suggested, or to select reverse.
When you are more familiar with it you could try being a bit proactive. On steep hills with lots of bends, both going up and down, I invariably select manual mode. This allows you to select a lower gear as you approach a hairpin bend. Left to its own, the gearbox, which cannot see the road ahead will very likely enter the bend in too high a gear (if going up the hill) and you really don't want it changing down under heavy load on a steep hill - worst case the vehicle can virtually stop before it has changed down. Second to first under load is to be avoided if at all possible - anticipate the change before you enter the bend.
The "Up" button seems to work best on heavier vehicles but all it does is hold lower gears than it would otherwise. It cannot anticipate the need to change gear. I tried it a few days ago on a very steep and wiggly hill in Sicily, both going up and going down but wasn't convinced so I went back to manual changes. Ours is 3.5t - so a lightweight.
Thank you so much for your comprehensive reply. In fact, it makes so much sense I am going to print it out and have it close by until I become more accustomed to the automatic gearbox. I did notice at one point whilst driving last weekend (I think I was going downhill), that the gearbox seemed to switch all by itself, from automatic, and select 2nd gear which was a bit alarming, however I swiftly knocked it back into automatic and all was well. I feel I definitely need to master it before attempting known hilly/steep/winding roads.
I absolutely love my new MH though.....very spacious and so much more practical than my last one. What is it? A Burstner Ixeo 680G. I am planning on leaving for sunnier climes in February 2018 and cannot wait.
Wishing you all happy and safe adventures ;-)