When modeling the roof you want to only model the overall construction of the roof and not try to design the specifics. That will come in later. Model everything in the roof construction minus the tiles/shingles as they are not necessary for this step and will only get in the way. But add a shingle texture after for presentation.
If the roof is very complex or you are on a tight schedule don't worry about the roof segments intercepting each other. This stage of the design it doesn't matter any interior interceptions because all you need for this are the exterior elevations and if you make it too complicated it will make it more difficult to change it in the future.
The key is to keep it as simple as possible to make future changes go faster and with less time-consuming problems.
Make very rough estimations for the roof then clean them up before sending it to Layout for elevation and renderings.
For making decks and patios you want to bring your building back into the terrain model to reference it and decide how to go about creating them as it plays a huge part in placement and size. Like modeling the rest of the house only design the outer frame of the deck and not the finishes on top.
Making windows you only want to create a simple rectangle cut out and apply a glass texture to it or if you already have a window model you can bring that in but only do it if it's already cut to size. Don't spend too much time getting the exact framing of the windows and focus more on the whole shape.
Doors are slightly different. You want to cut out the size for a generic door and then model the approximate thickness of the door and rotate it in the middle of where it would swing. For example, if your front door swings inward when opened you would have it on a 45-degree angle inside the house and etc.
For doors, you want to be more precise and get the trim done (nothing fancy just a simple rectangular shape around the door) to emphasize the size