Every day, future cellists contact us with their life-long dream of playing the cello. That's what we are here for; to help you realize that dream. Cello is an amazing instrument with wide appeal, so we aren't surprised by the number of adults, many now seniors, who want to play cello. Here are some tips, opinions, and information that might help you realize your dream.
Experienced musician: if you are already a musician, even if you haven't played anything in awhile, this will be helpful as you learn cello. You probably know how to read music, already have a good ear, and understand the process of learning an instrument.
Having played a number of different instruments myself, I can say without reservation that cello is, by far, the most challenging instrument I have taken on. It's not an instrument that you can learn without instruction. There is so much to the ergonomics of your posture, the left hand, and the bow hand and arm that without feedback from an experienced teacher you are not likely to get a decent sound from your instrument, and could be setting yourself up with very bad habits that will be harder to break later on. Repetitive injuries are also possible if you are doing things wrong.
One drawback of being an experienced musician is that you are probably already good on something else, and your expectations may be a bit out of whack. For example, without understanding how to hold the bow, and how to move the bow arm, your first attempts at playing are not likely to sound very great. There is much more to playing than just dragging the bow across the strings. It doesn't magically sound good; there is a lot of nuance to the bow, which is, as Linda says 'the real instrument.' Learning proper bow technique will set you up to have great tone...eventually.
You will not be Yo-Yo Ma out of the gate, unfortunately. But if you are serious about learning, my biggest advice is GET A TEACHER! In-person instruction is best, but if that's just not possible, virtual is better than nothing. My issue with virtual is that your teacher can't get a 3D look at your sitting position, or either of your hand positions. There are some great instructional videos on youtube which might get you started if you are really good at self-critique, self-correction, and you have a mirror so you can see what you are doing, but you should only rely on this as a stop-gap while waiting for your first lessons.
So, for musicians, don't expect your first notes on the cello are going to sound anything like our recordings (which are done by a professional who has been playing for over 50 years). And getting weekly instruction, and being motivated enough to practice daily, are essential to real progress.
Never Played an Instrument Before: as a new musician, you will have your hands full learning the cello. But if you really love the sound, and are highly motivated to learn, anyone can learn to play! A good teacher is essential; this is not an instrument that you can just doodle around on and expect a good sound.
Learning to read music as you learn an instrument with so many 'moving parts' is going to really make your mind work. There are no frets on a cello, so learning where the fingers go for each note requires hours and hours of practice so that you get 'muscle memory' for the hand placement. And of course, instruction on what a proper hand shape looks like, where your arm is positioned for proper intonation, and the importance of the use and position of your left hand's thumb.
The bow is a different story. The position of your right arm (your bow arm) is totally different on each string. Watch some videos of professional cellists performing and you'll see what I mean. It's a very physical instrument to play, so you also need to be fairly able-bodied and flexible. If you have a lot of arthritis in your hands, it is going to be challenging for you.
Since you haven't played anything before, you may be a step ahead of experienced musicians in that your expectations may be more in line with reality than theirs, or not... I, myself, am aware that my expectations about things I have never done are rarely correct. So, be prepared to be humbled by the experience of learning cello, and have few, if any expectations of how amazing you are going to sound. If you are willing to practice every day, and attend weekly in-person lessons, in a few years, you should be sounding pretty good. If you don't have that sort of time, there are much easier instruments to play such as the guitar, that will give you more immediate success.