Sorry I did not jump in earlier, as this is a topic that is close to my heart.
Bottom line for me is this: you get what you give (noted by Seb). And I know that is not universal, but it is certainly a good start.
If you adopt a positive tone in your dealings, you'll find that you get a good deal of the good attitude back.
Now I do have to take Superfly (one of the most civil people, on a one-on-one basis, I have ever had the pleasure of meeting) to task for a couple of things.
First, civility is not a political party thing. There are plenty of jerks to go around on both sides of the aisles, and I'd suggest that the entitlement mentality so prevalent in the welfare-state liberals is scarcely conducive to politeness (By the way, Sam Walton was a lifelong Democrat). If you observe who on these boards calls those with whom they disagree by offensive or belittling names, you might find the political slant to be other than as you have suggested. But that machts nichts.
Second, there really is a big difference between the attitude one finds in south OC vs. the north county towns. I worked in [the People's Republic of] Irvine and my wife, in Newport Beach, but when we went home, it was to Fullerton. No, it was not cheaper, but the neighborhood was a fine mix- all ages, races, a great mix of folks, and we genereally knew what was going on, on the street. Indeed, that neighborhood (adjacent to CSUF) is one of the few things I miss about living in SoCal. It reminded me of my neighborhood back home in Dallas, the one in which I grew up and where my folks still live.
I strongly endorse the notion of patronizing smaller, locally-owned businesses over national chains, and I agree that the tendency towards more remote and larger businesses is not a big help in this regard.
The biggest cause of lost civility is, and shall continue to be, the breakdown in effective parenting (whether by single, married, or same-sex parents, so save the attacks). A whole lot of touchy-feely-moonbeam parenting has produced a couple of generations of offspring for whom the apparent consequence of poor manners and strident demanding is... ummm... getting just what they want. Behavior is learned, some by teaching, more by example, and the example being given these days stinks. It is often tough for me to explain to my son that he should do the right thing, because it is the right thing, whan there is another kid his age getting a pass from his folks. I know (or naively believe) that my son will be better off for it in the long run, but in the mean time, it is a lot of work.
I could go on, but it all makes my brain hurt and, being the greedy capitalist that I am, I worked for six hours today so I could help continue the company-funded health insurance and retirement plan which I, as a greedy Republican, provide for my staff (and which I, if taxed any more, will be unable to afford to provide).
...three miles from BRONS, clear for the ILS one five approach...