I fell into working with wine by accident. I'm 25 and about two years ago I thought there was red and white wine and that was it. Now I can talk about it comprehensively and love the different types and finding out and learning about it.
I got into it because I work in hospitality. I began working somewhere in the back of house department, with had the cellar within the department. I worked in the cellar part of the time and began learning about wine. When teh chance to work in there full time came up I took it and have been learning about wine and writing wine lists ever since.
I have found that the best and most recognised training comes from the WSET (Wine & Spirits Education Trust). The intermediate certificate is a good starting point. I am about to move onto the advanced certificate which is quite well recognised and therefore something that will really aid me in my career progession towards becoming a wine buyer.
My situation is a bit unique, but I would maybe suggest getting on a wine shop/merchants management training scheme or once you have the WSET advanced certificate becoming a part time wine consultant with someone such as the following people
http://www.thirtyfifty.co.uk/
Hope this helps!