Who are you when you queue?
I think lines are great. In a world of varying ideals and philosophies on situations in everyday life, lines are universally accepted as bringing order to public society. However, as good as lines can be, they also are a source of great frustration for many people. Thoughts about the people in front of you: "I really wish they would keep their kids under control ... Are you kidding? Is he really writing a check? Has he ever heard of a debit card? ... I only have one item, she should just let me go in front of her so I can be on my way." Thoughts about the people behind you: "They are standing too close, I wish they would back off ... (Insert kid statement here) ... They have too many items to be in the express lane." Patience is the key, but even your Modern Manners Guy can run a little short on patience when queuing doesn't go so quietly.
Mind the Principles
Allow me to preface the following comments. Most of the examples I will use will be related to standing in line at a retail or grocery store; however, the principles can be applied to many different situations (e.g., drive thru lanes, buffet lines, lines outside a sporting event). It's important when queuing up anywhere that you take a moment to notice how busy the location is. If you are the only person in the store, then the rules can probably be relaxed somewhat. But, if there is someone behind you, be considerate of their time. I realize you may come to this store multiple times each week and can't wait to catch up with your favorite cashier, but this isn't social hour at Maximilian's Country Club. Who knows, the person behind you may be late for their own wedding and had to pick something up along the way. Make sure to come during the store's slow times, if you're looking to socialize.
Cut Out Cutting
There might be nothing I can say here that is more important than this: do not cut.