High Hopes
NO you are not too old to learn to dance - no one is too old to learn to dance!
#1 thing you need to get is a good pr of dance shoes. Hopefully there will be store that sells dance shoes in your area - go try on shoes. The brands fit differently so don't buy on line and your stuck if they don't fit right or feel good. When looking for dance shoes make sure they are the C version. This is the competitive shoe that has more padding on the bottom. It will cost a little more, but your feet will thank you! If your a female make sure you have a good stable heel not a thin stiletto heel.
Wear comfortable clothing that you can move in for your lessons. As you progress, if you are female your instructor may ask you to wear Latin skirts so they can see your knee actions.
Depending upon how many lesson a week you take in the beginning you might be sore as you build muscles. Epsom Salt bath soaks are your friend! When those stop working a good massage works well.
In the beginning you might feel overwhelmed with getting all the patterns down AND being technically correct. THIS IS NORMAL, HANG IN THERE, IT GETS BETTER. For me it felt like had an arm load of small balls I was trying to carry and one or two would always be slipping out. As you put these patterns and move into muscle memory you will find you have fewer balls in your arms.
Go to social dances to put to practice what you've learned in lessons anbd have a lot of fun!