Are you thinking of anything else or looking elsewhere as you come to a stop? Think of just the stop and getting one or both feet down as you come to the stop. You can use the front brake for the last few inches of travel, get off the rear brake, and get your feet down and the bike held straight. Yak has a very good point about stopping on a side-sloped piece of road--be sure you are supporting the bike's weight on the foot on the high side. Practice. Find a very minor grade and practice. Then practice on a bit more grade, then even more.