What black magic do musicians use that ensures their fingers always find the right notes? C’mon, no matter how much you practice, it simply amazes me musicians never hit a clunker. And, I don’t just mean professionals. I mean that guy at summer camp with the guitar or banjo. The perfection in fingering just seems to defy all odds no matter how good one may be…and they don’t seem to be staring at their fingers the whole time, either.
Any musicians care to share their trade secrets?
There’s no trade secrets. It’s practice, practice, practice and muscle memory. And musicians do hit wrong notes from time to time; it’s often not that obvious, and sometimes you can make a wrong note sound intentional if you play it with enough conviction. 
The ones that really baffle me are fretless string instruments, and also the trombone. How do they know???
Secret: Don’t play songs which you haven’t practiced yet.
Do you stare at the keyboard when you type?
I just picked up my trombone for the first time in 5 years, and joined the alumni marching band to play some songs I hadn’t played in 15 years. With just about an hour of practice I was able to play the school’s Fight Song with no music.
Lord knows I practiced and played that enough back then to remember it.
Here’s a secret about trombone, though - there are only 7 positions. One of them is 1 and it’s closed. Not hard to remember. You don’t really use 7 or 5 at all. Position 3 is before the bell and 4 is after the bell. Position 2 is inbetween the bell and closed. Position 6 is “almost as far as you can reach but not quite.” Mostly you’re going between 1 and 3, changing your ambrochure depending on the note. Just gotta remember to hit 2 or 4 when there’s an incidental and you’re golden.
Valve instruments aren’t much different IMHO. I play baritone for Christmas and you’re pretty much just hitting 1 or 3 or 1/3 with a couple of incidentals thrown in.
Strings instruments and piano, though - those people are geniuses!
I used to play bass in a band and I found I was much less likely to make mistakes when we were playing in front of an audience. I’m not sure why, maybe the adrenaline or something helped. But I did find that when I did hit a bum note, or even if the whole band lost its way slightly, nobody ever seemed to notice.
Hell, I do. And I’ve never been able to play an instrument, either.
When I was a kid, my best friend was a piano prodigy of sorts, and I’d sit in the music room with him after school and listen to him practice a piece over and over (great time to do homework or read). Repeat for a few weeks. I’d get so used to the song that even I could tell when he hit clunkers; I’d wince at a recital when he hit the wrong note, and afterward when everyone was congratulating him, I was usually the only one who knew why he was dissatisfied with his performance.
This bears repeating. You practice until you get it right, and then you practice some more until you get it right every time, and then you practice some more until you can get it right in your sleep. Non-musicians often don’t seem to realize how much time and effort goes in to being able to play an instrument even competently, let alone brilliantly. You can’t just sit down at a keyboard and play Rachmaninov the first time.
I think you may not realise just how much practice is involved. For a couple of years I used to practice guitar three or four hours most days. After all that drilling your fingers just go to the right places.
It’s not original but this about sums it up:
An amateur practices until he gets it right.
A professional practices until he* can’t get it wrong.
Learning to play, and playing well are two different stories.
In my youth, I played guitar. At one point, I was decent. However, as mentioned, it is practice, practice and more practice to get over the hump of simply being able to play the chords/notes, and being able to gracefully and effortlessly.
I like Dorjän’s analogy of “do you stare at the keyboard when you type?”
Most people can type - some have to look at the keyboard and maybe use two fingers, others can type like crazy and never once look at the keyboard.
Same for playing the guitar. Some can find exactly the right positions when they need them, and know exactly where every finger needs to be at the exact right moment. They can run around stage, sing, dance, wink at the cute girl in the front row and never miss a note. Others need to look and move their fingers and hope to be in the right spot at the right time. Practice, my friend, practice.
Oh, and it does help if you have at least a modicum of talent and rhythm.
“Amateurs practice until they can get it right;
professionals practice until they cannot get it wrong.”
I know this is a quote from someone, but darned if I remember who.
ETA: Shakes fist at Small Clanger
[QUOTE=Noone Special]
I know this is a quote from someone, but darned if I remember who.
[/QUOTE]
Me two minutes ago 
Nah, I got it from a book - Adrian Legg I think.
Hee hee.
Then you mustn’t like to practice, because it really is true, that practice makes perfect.
Also, the greatest of greats do indeed flub, on the odd occasion.
Human, and all that.
What amazes me is virtually all professional musicians are able to record albums that are musically sound (even though they may be lacking in taste). It seems like there would be at least some that would become famous based on their image or songwriting but would be unable to keep a beat, play their instruments or sing in tune. Maybe they use studio musicians more than is credited.
Practice.
When I was in HS band I set it upon myself to learn how to play the scale on every instrument in the orchestra. Trombone was one of the easiest.
Welcome to pop music.
Autotune must die!
Yep. I think non-musicians don’t understand the vast amount of drudgery musicians go through to make it seem so effortless. And if you’ve practiced enough, it is pretty effortless. When I played (drums) in a band, I was the only member who was over 21, so when we went to clubs and got our free pitcher of beer, I was the only one who could drink it, and, as a consequence, played a number of shows fairly drunk. But it was all muscle memory by that point, so I could still do my job pretty easily (barring non-ideal situations where the clubs had no monitors, when I couldn’t hear the others and had a tendency to speed up). When you’ve got it down that tight, you don’t even have to think about it. It’s like walking or breathing.
There are only 7 positions on the trombone slide. There are points of reference on the slide that help beginners to learn the positions. 1st is all the way in, 3rd is when the slide handle is underneath the bell, etc. At each position pitch is changed with the embouchure. Beyond that, as has been said, it’s just practice and repetition.