Getting a good drift is one of the most important aspects of fly fishing. You can have an exact imitation of the fly, the perfect rod and reel combo, a 100 dollar fly line, excellent sun light, or overcast day, and complete visibility of a fish, but you can still get it all wrong. Even without spooking the fish!
Your drift determines everything.
On a recent trip I set a fellow up with a 9 foot nymphing rod over a pool I knew held a lot of trout. By himself, he cast, cast again, and cast again with no success. I watched his efforts then told him where to cast, and how to remove some of the drag he was experiencing. I watched him as he clearly thought about what he was doing and focused on where he placed his flies. He performed a necessary slight mend then made sure his nymphs were drifting naturally in the water.
On that cast he picked up a fish.
Every time he cast into the wrong seam and let drag persist from the start, the indicator would float about casually showing nothing was interested. When he would spend the extra focus to cast into the seam (on the edge of the fast water and the slow water), hold his rod tip high to remove unnecessary line on the water, and remove drag with the minor mend the fish were eager to take the fly.
This goes to remind you, drift is essential to your presentation.
To further this point let me tell you the rest of the story. After my friend had covered most of the pool I decided to cast a few times into the pool in a few of the more tricky sections he hadn’t hit. Let me remind you, I am not the best angler nor am I bragging, I've just fished a good bit longer than he has and gained a little knowledge from experience. After watching him for a while I had a good feeling we hadn’t put the fly in front of every fish there.
I practiced what I preached and focused on where I placed the fly and what the fly did when it was in the water. The fly drifted naturally in the current on the opposite seam from where he covered, and immediately, my white, yarn indicator plunged into the water. I set the hook into the jaw of a chunky foot-long brown. I cast a few more times in the same manner and changed a few things on my rig. On the first cast after I moved my indicator 4 inches farther up the leader I fooled and landed a beautiful, strong, rainbow trout with the net work of my friend (pictured above)!
I was using the same flies as my friend was, the same rod he was using, it was the same weather, no huge changing factor, other than the extra experience I have from fishing for many years. Keep in mind, the two fish I landed in 5 minutes had seen a fly in front of their face quite a few times from my friend, but for some reason they never took the fly.
The conclusion I have come to is, the drift wasn’t how the fish wanted it.
Getting a proper drift has one of the biggest impacts on our fishing, nevertheless, it is widely neglected or over looked because it's not quite as sexy as tying perfect flies, taking cool Instagram photos, and hoarding the most recent gear. If you really want to catch fish, I urge you to focus on your drift. Of course you can tie perfect flies, take cool pictures, and get new gear, but first focus on your drift.
I believe reading water is one of the primary keys to getting a good drift. Educate yourself on reading water and you will be able to better understand drift, drag, and what drifts are good, bad, or just plain stupid. There are some excellent books and videos out there on reading water - ingest them and don't forget them while you're on the water!
My bottom line is, don’t mindlessly cast into your local river and expect to catch heaping amounts of fish. Read the water. Ask yourself where you should cast, and cast there. When nothing strikes, cast there again with a minor change ensuring your drift is as best as possible. It will surprise you how many fish reveal themselves when you actually focus on what your doing, present the fly properly, and are willing to constantly change your rig.