Just a level set from someone who has been playing since the early 80's and has been a pretty solid player for nearly as long; the open C chord is a deceptively difficult chord to play. It's the index (pointer) finger that gets you.

Yes, it seems like an easy enough chord but that index finger wants to pull the other two down and away. If you have average sized hands, it is the challenge.

I've never really played an open C chord that I felt comfortable playing. You wouldn't know it. But it is pretty much my least favorite chord. So much so that some songs I've performed in the past, I will choose a slightly different C shape so that I don't even have to mess with it. On top of that, a year or so ago, I had an odd series of mild issues/injury with both index fingers and that hasn't made it any easier.

Discouraged? Don't be.

First, just know that while you think it should be an easy chord to tackle, it's not as easy as you think. You can overcome it and will likely play it better than I do. Still, it's helpful to know that if you feel a little challenged by it, don't be discouraged since it's not as easy as it would seem.

Second, remember that you have real estate between the frets, use it. Spend a little time actually fretting the C chord and look where your fingers (any of them) are between the frets. I find that my index finger wants to be right up against the first fret (B string) and my ring finger wants to be right up against the second fret (A string)....my middle finger just goes wherever it seems to land. There is an awkwardness of the chord angle because your index finger wants to the pull the others.

A quick experiement; put your hand out in front of you (in the way you might look at your finger nails), bend your index finger down at the first knuckle (the one that attaches your hand to your finger). Notice that the other fingers have a 'reaction' in relation to the movement of the index.They are tied together by your hand and when one moves, the others will react in some way. They are not independent. Something to keep in mind.

I do play a good clean C but I never love actually playing it. I just noticed over time that the configuration above got me there after playing over the years.

One other tip on fingertips mentioned by manX; it takes very little pressure to make a string ring true. You need just enough tension in fretting for the string to lay solidly on the next fret and no more. You don't need to try to push the string through the fretboard. You're pushing too hard then. Experiment with how little perssure you need to fret a note. You'll be surprised. Your wrist and fingers will come to appreciate it too.....