Know as much about the trout stream as you can. Know what hatches may be occurring at various times of the year. Know which species of trout are present. Try to develop a knowledge of fly types that work on the water you will be fishing. Whether streamer flies, nymphs, or dry flies, try to get as specific information as you can get. Know specific colors and sizes and have as many of those sizes as possible.
This information is available on the internet through regional forums as well as traditional websites (see resource box below). Also, local fly shops are a great source for information and doubly so if you have the courtesy to actually make a purchase relevant to the advice you receive. This is kind of analagous to hiring a fishing guide. You may pay a bit more for your purchase the first time, but you then have gleaned the information you need to make future purchases via discount retailers if you so choose.
Approaching the Water
You cannot go splashing into the water and start looking around for a good spot to fish. Reading the water is best done from a short distance back and is not a snap decision. If the water is clear enough where you can site fish, this means they can see you as well. You may have to make a crawling approach at times. You need to make a decision based on your own skills. Great water with an overhanging bush is not an option if you cannot roll a cast into this water.
Depending on what you will be fishing, dries or nymphs/streamers, make a wise decision on the water you will fish. If you will be fishing dries, and you are a beginner, consider a slower current stretch where you can get a longer drift before drag starts to affect your line. If you will fish pocket water, think about drifting your offering into the pocket in the manner the current will naturally bring food downstream. This is usually done while fishing nymphs. Whether you use a strike indicator is a personal decision, but may be helpful for the beginner to detect strikes.
I am not a dry fly purist. I enjoy most catching fish that have risen to a dry, but if the fish are not rising to a hatch, I have no qualms about fishing below the surface. In fact, generally speaking, I fish streamers and nymphs unless I see a reason to switch to a dry. Once trout begin rising to feed, then I will usually switch to a dry. However, there are even times, say when there is an enormous hatch and very few fish are rising to feed, when I will stay with the streamers and nymphs. If there are millions of critters landing on the water and only a few fish rising to them, what chance does my one elk hair caddis or adams fly have?
Often, I will begin fishing the early part of the day with nymphs and streamers in pocket water and deep pools. Often I will switch quite a few times and then hit on something where every drift is eliciting a take. When this stops producing, I assume that the fish gods have told the fish to stop biting, stop biting that fly, or I have sufficiently disrupted that stretch of water. I will usually try a few additional offerings, and if I have no success, move to a new stretch of water.
As evening approaches, I am particularly alert to hatches and/or rising trout. There is nothing more satisfying than a take on a dry. If possible, be able to identify the hatch and/or what the trout are rising to, and as they say, "match the hatch." Sometimes a rough facsimile of the hatch will suffice if an exact match is not at hand. Be willing to experiment. Often, very subtle differences matter. Even for an experienced fisherman, a new body of water can be a challenge. If you are pretty sure that the stream holds fish, be willing to go back a few times even if at first you do not have success. Just like your casting skills, your other fishing skills will build over time, and there is a lot of satisfaction in becoming well versed in a certain body of water.
We hope the tips serve you well.