Tammi Kastelnik wrote:

I've been running for about two years, and I am training for my first marathon. I'm starting my long runs (12+) and I'm having a hard time controling my breathing. I'll take a few quick breaths and then take a long breath. I feel like it's impacting my run and I'd like to learn some breathing techniques. I am open to any suggestions. Thank you!

I don't think there's a scientific answer to this question, and I've only read one serious discussion of the issue.  But . . . most runners breathe in time to their foot falls, the most common is in on two steps and out on two steps.  This seems to be particularly applicable to long runs and daily training runs, though I find it works for speedwork and the like as well.  One thing you might consider is you are going too fast.  I sometimes find myself taking a few short, quick breaths followed by a long one, and it is always when I'm pushing the pace.  Your long run pace should be one to two minutes per mile slower than your planned marathon pace.

Len