There are two main problem areas: hills and starting (three problems if you combine starting off and a hill). In either case, change to a lower gear sooner rather than later and make Turbo assist your friend.
When you come to a stop, remember to change down to a low gear. If you forget – we're fallible, aren't we? – start off with Turbo assist and wait until you're moving at a walking pace before changing gears.
On hills, try to keep turning your pedals through 360º every second (60 rpm). Two seconds (30 rpm) is too slow. Click down through the gears before you are straining! If you are caught out, use Turbo assist to increase your pedalling cadence.