Getting on everyone's nerves around you and having everyone get on yours can be quite a pain. Soon you end up losing friends and family members start steering clear of you. Learning to stop being irritable can be quite an exercise in self-discipline.
Learn to accept: Most often, we do not like situations around us. We want to change our workplace, our spouse, our city and almost everything we do not like. Learning to accept things as they are and helping yourself realize that there is just so much that you can control and change will help you become less irritable. When you grow out of your 'child ego' as psychiatrists would say, you realize that the world is not of your making. There are limitations to what you can alter and usually these limitations are limited to yourself. The moment you start thinking about improving yourself and not being bothered about how others behave or react, your irritation will start melting. The idea is not to be confused as in compromising with people and situations but to rise above them.
Physical fitness: Ensure that you follow some kind of a physical fitness regime. Hitting the gym regularly or taking up yoga at a studio near you will go a long way in not only building your physical abilities but your mental tenacity as well. This will, in turn, stop you from getting irritated easily. You can also take up some hobby classes that will keep you focused on your own activities and achievements rather than other people and their actions.
Selective interactions: Become selective about friends and people you interact with. This is not to serve like a kind of ego-based classification process of people you meet but just being careful of people who tend to put you into a negative mood by their criticisms and comparisons.
Meditation and spiritual progress: Start learning special breathing exercises for relaxation, different types of meditation for centering your attention, laughter therapy or any such New Age techniques. Soon, you will have no clue how you transformed into such a cool creature.