What are some ways to improve my practice? I meditate for 30 minutes each day, focusing on the feeling of my breath moving through my throat. When I am not meditating, I try to mentally "say" whatever it is I am doing (e.g. if I am angry, I say "angry" in my head). I also adhere to the five precepts. I have been following this routine for about six months now, and at this point I feel like I am seeing fewer results than ever before. I often am unable to maintain focus for the full 30 minutes or even a substantial part of the meditation time; I still find myself becoming irrationally angry towards people...it is discouraging.
How can I augment or change my practice to find peace and be less angry?
Thx!
It is hard to offer concrete suggestions or even precisely guess what's happening without more information about your practice and your background;  that said, it looks like your practice is sincere, and it is working. Often when the practice begins to bite, irritability and impatience may increase - it is a learning moment, and a teacher. Find the three characteristics of impermanence, non-self and suffering in each of those moments of irritability, dullness and anger.

Without getting into too many technical details, I'd say, think of it as the next level in a game, your opponents are tougher, and that is what makes it more interesting.

The most important thing is not to abandon practice at this point, but to continue, this is exactly when you need faith and perseverance. 

I assume you practice insight meditation (also called Vipassana), if you do, it is not about indulging in the pleasant moments, or treating ourselves to some peace and calm - it is about understanding reality - which means one encounters the good and bad mind moments, and learns to remain equanimous.

Everything is impermanent - even the good and calm times in meditation will go away, and be replaced with difficult times - this is the moment of wisdom, that reveals the suffering in being attached to any feeling.

You might want to take a look at another question where I've offered more advanced help - Working with cycles in meditation . Stop reading it if it gets confusing.