Fly fishing is more than simply casting a fly to a waiting fish in the water. Fly fishing is as much about the why as it is the how. In other words, fly fishing is a state of mind. Sure, it is important and enjoyable to catch a trout on a summer afternoon. However, it is just as important and enjoyable to practice proper etiquette while getting to the water, while on the water and when leaving. There is a reason why fly fishing was for many years considered a gentleman's sport. This is not to infer only men should participate. Rather, it is a sport with tradition, courtesy and stewardship.
When walking to a section of water, make sure to stay on existing trails and resist the urge to take a shortcut that may damage existing undergrowth. Do not leave anything behind that does not belong there. All trash, including wrappers, paper and even cigars, should be packed out. Do not trespass. If property is marked, then stay clear. Also, make sure you read and understand all fishing regulations--do not fish unless you clearly understand the rules. When approaching others fishing on the bank or in the water near the bank, approach quietly so as to not disturb them or spook fish. The water belongs to who is fishing at the time, period.
On the Water
Only wade when it is necessary. Try to disturb as little of the ecosystem along the bank and in the water as necessary. Avoid entering a stream or creek directly across or immediately upstream from others who are fishing. This may spook fish or create silt that will deter fishing. Keep in mind that there are rules for right of way on the water. A person fishing upstream has the right of way to someone fishing downstream. Making conversation is perfectly acceptable when asking the other person how he is doing, his fly selection and so on. It is also perfectly acceptable not to speak. Practice catch and release by understanding and using good techniques, including the use of barbless hooks.
Odds and Ends
Encourage others--especially youth--while fishing. Do not offer advice where it is not wanted, and provide positive feedback when it is. Offer assistance to others who may be experiencing difficulty with equipment or who may be beginners at fly fishing. Once again, use care when offering advice and help. Practice good stewardship when possible. For example, if trout are spawning, avoid the temptation to fish these areas. Take advantage of the opportunities that present themselves to promote the sportsmanship and stewardship of fly fishing.