Hiking etiquette is really pretty straightforward -- it's not like you have to know a secret handshake or code word to get through to your final destination. Still, if you don't want to see other hikers cringing as you approach, there are a few basic rules you should observe:
For All Hikers
Don't be obnoxious. A certain level of noise is appropriate for scaring off dangerous wildlife, especially if you are hiking alone.
But don't be so loud and rowdy that you scare off other people, too.
Never fake distress or any of the other bad, bad things a hiker should never do.
Mind your potty etiquette. Nobody likes to see bunches of white toilet paper scattered along the trail or in the woods. If you have to wipe after you urinate, pack it out. If you have to defecate, pack it out or make sure it's properly buried, away from the trail and water sources.
When Hiking With Others
Show up on time. I will admit to breaking this rule more than I should -- but at least I do my best to give notice if I know I won't be able to make it on time, and I grovel appropriately if I show up unacceptably late.
Come prepared. Unless it's been arranged in advance, never count on others to bring gear, water, clothing or food for you. It's your responsibility to make sure you have the proper footwear, the ten essentials, and have packed any additional comfort items you might want. (Food is good!)
Play it cool. You're about to deliberately isolate yourself with people you might or might not know very well.
Talking amongst yourself is a great way to scare off bears and other potentially dangerous wildlife -- but try to avoid hot-button issues like politics and religion, unless you know each other well enough to be sure you'll still be on speaking terms when the hike is over.
Keep an eye out for each other. You don't have to micromanage your hiking buddies (please don't) -- but do be aware of what's going on around you and, if you see someone struggling, see if you can help. The group is only as strong, safe, and fast as its weakest member.
Don't plan to mooch food from your buddies. Just don't. Nor should you deliberately "forget" to pack your stove or fuel, then spend dinner prep time gazing soulfully at your buddy's stove and hoping he'll let you use it.
If you agreed to share meal duty and it's your turn to cook, don't make Ramen noodles or settle for freeze-dried mush. At least try to make it look like you made an effort.
If you know you snore loudly (or do anything else that might antagonize or embarrass nearby tent-campers), pitch your tent a respectful distance away from others. Make any excuse you want. If you know you're going to be camping in close proximity to others, at least serve fair warning so they can bring their earplugs.
Verify the presence of all required tent parts, especially tent poles, before you hit the trail. Nobody wants to end up spooning with you in their one-man tent just because you couldn't put yours up. Nobody.
For Dog Owners
Don't let your dog off-leash unless it truly responds to voice control. (Even then, there are some good reasons to keep it leashed.) Your surprised indignance when you try, but fail, to call your dog back isn't fooling anybody -- especially not the other upon hiker whom your dog is currently jumping. Look at it this way: In some places having an out-of-control dog really will get you a ticket. And other places? Your dog might come tearing back to you with an enraged bear or moose hot on its tail or, worse yet, not come back at all.
Don't automatically assume that other dogs are friendly. Most dogs you'll meet on the trail are footloose and fancy-free, happy to meet every dog or human that crosses their path. But not all of them are, so be alert to signs that another dog owner doesn't want your pooch getting too close to his -- yet another reason why it's so important to keep your dog under control.
Do pack out your dog's waste. You should dispose of it as you'd dispose of your own feces -- pack it out or properly bury it away from water sources. If you refer to do that, at least make sure your dog does his business off-trail. But even then, dog feces can spread disease -- and stepping in a doggy landmine is even nastier when it's hidden off-trail.