The timing of your breathing is something that is often overlooked by coaches and swimmers but can make a lot of difference to your ability to get a clear breath and also improve your level of relaxation in the water. When a swimmer rotates to breathe, the head should rotate and slightly lead the body rotation. Here's Jono Van Hazel from our Catch Masterclass DVD demonstrating this:
Many swimmers breathe late and rotate their head slightly after their body rotation, from the pool deck you can see this as a flicking movement of the head as the swimmer has to suddenly rotate their head in a hurry. Breathing late leaves you with a much shorter window to breathe in and you will still be trying to breathe as your recovering arm enters the water - which you might feel hitting your nose! :
Even advanced and elite swimmers can suffer from this problem and is something they can work on. A good visualisation to develop correct timing is to think about 'turning your head away from your hand' :
As your recovering arm and hand enters the water, turn your head away from it to breathe, as if you are trying to avoid seeing it. By doing this you will find you are in a breathing position much earlier giving you plenty of time to inhale smoothly. Of course, you should also make sure that you're exhaling into the water between breaths so that you only have to inhale, not exhale and inhale in that short window! See here.
One other observation: If you have a strong preference for breathing to one side then it's much more likely your breathing will be late on that side. On your non-preferred side you won't have any bad habits in place and your breathing timing will probably be much better: As you swim, see if you can compare the movements of the two sides and see if you are indeed breathing late to your preferred side.