Don't let little things that other people, through their own opinions, do that really piss you off, actually get to you further than simply making you grind your teeth.
Example, someone on this website does something that continuously irritates me to the point of wanting to cave their skull in, but, I learned during my teen years that while having an opinion is fantastic and makes you unique, it doesn't grant you the right to voice it.
So basically, don't voice your opinions if it's going to be a negative one or a hurtful one, just let things go. It leads to a general miserable outlook on life where silly, pointless things that have nothing to do with you, bother you. Probably leads to larger issues along the line, all because you get involved in stupid pointless things that can pent you up.
So the next time you see someone/something doing something that irritates you, exercise restraint. You might live to be a little happier.