I recently saw a couple of episodes of Jericho per Triton's recommendation. Seems like a decent show altho I have come to it rather late in the series. Having seen the last two episodes only and having a bit of a discussion of a similar topic over at Nate's I thought I would throw in my two cents.
Preparedness: The Boy Scout motto is "Be Prepared." What is seen in this show is that no one is prepared. This is exactly where we are in modern society. No one is prepared for the adversity that comes up in this show. Being attacked by a neighboring town, granted a much larger town, is something that they don't know how to handle or even where to begin.
Food: The conflict is over resources and particularly food. They cannot grow enough to provide for themselves. The comment is made by the attacking town's leader that they are "too desperate to give up" and that is exactly how it would be. Many resources can be done without, but food and water cannot and their lack would drive some extreme behavior. Part of the point here is that larger towns cannot provide for themselves, and of course cities don't stand a chance.
Fighting: Even the preparations for fighting that Jericho makes in a defensive area are pathetic. Perhaps not unrealistic as far as what people with no training might do but there are simple measures that could be done to make an area more defensible. Foxholes being a great start. Sniper positions being another. One of the characters "heroically" makes a run for the top of a hill dodging bullets the whole way when there should have been snipers in place from the beginning. The higher ground would have completely negated the advantage their enemy had in being prone.
Stockpiles: One of the characters, I think ex-military/spy/spec-ops but I havent seen enough to know, had a storage unit full of firearms. Without this stockpile (enough to fill a pickup bed, which is totally realistic for a personal stockpile) the town would have been nearly unarmed. Your own personal stockpile would be a much better option than hoping some full-fledged paranoid had weapons that he would be willing to share, which he most likely would not.
I know it is just a show and it has to be made interesting and all. Just giving my initial thoughts on it.
Also something that I mentioned at Nate's was a need for different crops, assuming you had land to grow things on. There is always talk of being self sufficient but in a farming community you will often find that there are very few crops being grown. This is due to the climate and soil, the current market for crops and the foods the farmer has experience with which is likely to be much the same as everyone else in the area. I think branching into different crops than are common in the area, but that still grow well, would be an advantage as then you would have something that others would want to buy/trade for. My first thoughts are vices. Tobacco, marijuana, and beer/wine would be good things to produce as they are always in demand in varying amounts and would grant a unique position in any market that springs up as one surely will.