I prefer a toothbrush with medium or soft bristles. The hard bristles tend to make my gums sore.
I also make sure I brush my tongue, especially in the mornings. That really helps get rid of bad morning breath. I have a toothbrush that has a textured, rubberized patch on the back, and it's great for brushing my tongue, the roof of my mouth, and the insides of my cheeks. That knocks out bad breath.
I've heard that the most important time to brush is before bedtime, so I always try to make a point of brushing my teeth before I go to bed.