Don't preset any mixing -BEFORE- you fly the plane.
See how much elevator and direction you need to hold it in flight, then set up the mix.
And don't look to slow down.
Flaps are more useful for steepening/shortening the approach, without adding speed.
You have to maintain a bit of power, as slowing the plane with flaps can lead to stalls.
Relying on them without using power to keep the speed up won't work for what you want.