As the madness of the city becomes ever-more pervasive, more people seek a wilderness experience to offset their urban lives. I do it. You do it if you are reading articles at this site. With the US population growing at one of the fastest rates for any developed nation, pressures on the wild areas through recreation, not to mention extractive industries, is increasing all the time. One of the most-cited benefits of backpacking among users is to achieve a sense of solitude that allows relaxation, connection to the surroundings, and enjoyment of the natural setting without distraction. In areas of particular scenic value, crowds can often detract from such an experience, yet they need not, if all who enter an area practice simple tactics. There are genreally recognized "Leave No Trace" tactics that everyone entering a wild area should attempt to practice. I've Typed in the Official Leave No Trace Guildelines, with my own comments added in green. 

Plan ahead and Prepare
Know the regulations and special concerns for the area you'll visit.
Prepare for extreme weather, hazards and emergencies.
Schedule your trip to avoid times of high use. This is the single-most effective means of assuring a successful wilderness experience.
Visit in small groups. Split larger parties into groups of 4-6.
Use a map and a compass to eliminate the use of marking paint, rock cairns or flagging. 
Repackage food to minimize waste. This will reduce the weight you have to carry.

Travel and Camp on Durable Surfaces
Durable surfaces include established trails and campsites, rock, gravel, dry grasses or snow. I would add pine-duff forest floor to this list, which is what I most often camp on myself.
Protect riparian areas by camping at least 200 feet from lakes and streams. My own opinion is that one should camp much further from popular areas like lakes, 200 meters would be better. If everyone did this, everyone would enjoy more solitude.
Good campsites are found, not made. Altering a site is not necessary. One of the great challenges of backcountry camping is finding the perfect spot. 
 

In popular areas:	Concentrate use on existing trails and campsites.  Walk single file in the middle of the trail, even when wet or muddy. Give those GorTex boots a workout! Keep campsites small. Focus activity in areas where vegetation is absent.
In pristine areas:	Disperse use to prevent the creation of campsites and trails.  Avoid places where impacts are just beginning.

 

Dispose of Waste Properly
Pack it in, pack it out. Inspect your campsite and rest areas for trash or spilled foods. Pack out all trash, leftover food, and litter. Pack out litter from those who left it before you. 
Deposit solid human waste in catholes dug 6-8 inches deep at least 200 feet from water, camp and trails. Cover and disguise the cathole when finished. Take time to dig a good, deep hole. If you start a hole and can't get it deep enough, due to roots or a rock, cover it up and move somewhere else where you can. 
Pack out toilet paper and hygiene products.
To wash yourself or your dishes, carry water 200 feet away from streams or lakes and use small amounts of biodegradable soap. Plant-based soaps are better than synthetics. Consider using a wet hankerchief for a sponge bath rather than splashing water. Scatter strained dishwater. Better yet, consider meals that need no cooking...like sausage and cheese, crackers, jerky. 

Leave What You Find
Preserve the past: examine, but do not touch, cultural or historic structures and artifacts.
Leave rocks, plants, and other natural objects as you find them. 
Avoid introducing or transporting non-native species. Non-native plants are arguably the greatest ecological threat to North America  outside of global warming.
Do not build structures, furniture, or dig trenches.

Minimize Campfire Impacts
Campfires can cause lasting impacts to the backcountry. Use a lightweight stove for cooking and enjoy a candle lantern for light. I haven't built a campfire in 4 years, and honestly I haven't missed it. I prefer to go to bed at dusk, and get up at dawn. Fires only keep me up late.
Where fires are permitted, use established fire fings, fire pans, or mound fires.
Keep fires small. Only use sticks from the ground that can be be broken by hand. 
Burn all wood and coals to ash, put out campfires completely, then scatter cool ashes.

Respect Wildlife
Observe wildlife from a distance. Do not follow or approach them.
Never feed animals. Feeding wildlife damages their health, alters natural behaviors, and exposes them to predators and other dangers. Practice hanging food at least 15 feet high and 3 feet away from tree trunks to stymie bears. Watch out for marmots and squirrels...they steal more food every year than bears.
Protect wildlife and your food by storing rations and trash securely.
Control pets at all times, or leave them at home. 
Avoid wildlife during sensitive times: mating, nesting, raising young, or winter.

Be Considerate of Others
Respect other visitors and protect the quality of their experience.
Be courteous. Yield to other users on the trail.
Step to the downhill side of the trail when encountering pack stock.
Take breaks and camp away from trails and other visitors. Read the last sentence again!
Let nature's sounds prevail. Avoid loud voices and noises. Avoid loud voices and noises!

I sum up my own ethics like this: I don't want others to know I'm around when I am, or have been when I've gone. Likewise I don't want to know if others are around when they are, or that they have been when they're gone. Nobody's perfect, and I don't claim to be master of these, but you and I both should strive to meet them all. It only takes one inconsiderate trekker to shatter the tranquility of an area, and I have unending disdain for folks like that.