I have been serious about real estate since I was 15, and I am now 26. I knew my age would mean hardly anyone would take me seriously. I compensated by focusing on my formal education and learning as much as I could about real estate. I majored in economics in college and did my senior thesis on my local real estate market. I then did a Master's in real estate. By the time I was done with school, I had saved up about $6,000 and used it as a down payment on a triplex, which I bought with FHA. (FHA requires only 3.5% down.) Just last month, I passed the CA real estate exam and am now waiting to finish the licensing process. I connected with a private lender last summer and am now working full-time rehabbing properties.
Moral of my story: 1) It is possible to find success even if you're young. 2) As many other posters have said, focus on your education. 3) Scrape & save every dime you can for a down payment. 4) Make your first investment the best you possibly can (ie: an income-producing duplex/triplex/quad rather than a SFR, for example).
I would also advise that you don't advertise your age to people you're trying to work with. It's immaterial to doing business--I can think of lots of other things you could say that are way more important.
Good luck!