I am 23 years old, And I started my education a year ago. No you are not old at all, the great thing about Theatre is that you can do it at any age. There will always be parts--no matter what.
I would reccomend several things (THINGS I AM DOING RIGHT NOW)-- 1) Go to School--and study for it. Some people just get Acting Coaches, However I believe that a structured acting program is better. You have shows that you usually can try out. 2) Audition, Audition, Audition--for everything!--In this buisness, Credits matter. ALOT, You have to have tons of experience to even get considered for some roles. 3) Get voice and dance lessons, if you are interested in Musical Theatre. 4) Read lots of scripts, listen to a lot of Musicals--there IS TONS of resources out there, I like to keep up with the trends and keep up with history of Theatre. There is more to Musicals than Phantom or Wicked or Rent.
Also remember, that people have been working on this for very, very long time. So it will seem very daunting and scary at first. You will feel very inferior if you havent done any acting. But if you have talent, you can make it. Also, know that you just cant walk on Broadway. First, you cant audition for Most Broadway shows until you get an Equity Card, And second You must have solid credits and acting experience to even being considered for it. So that's why I am saying Go to school for it. It's a very tough buisness, It's the toughest buisness in the world. There is THOUSANDS of people that have the same dream. You have to watch your back, but in the same time you have to make contacts and network. But audition, seriously for community stuff first. And stay presistent if this is your dream. But also know, that it isnt glamour and glitz. I am poor, very poor-- but I am very happy doing Theatre. Especially Musical Theatre.
I am not saying that this is you, but I find it funny that people think they can just walk in and be stars. It takes tons of blood, sweat, tears, dissapointments. I have had more turn downs than offers. And that's how it is, And that's how it rolls. Dont do it for the fame, Dont do it for the glamour or money--Do it for the fuffilment at first. Do Theatre for Free for a while, Because you are most likely going to be having to do it, anyway.
Anywho-- I hope this helps!