I personally would recommend going to a drama school if you have the finance and 3 years to spare. Both of which I currently do not. If I knew I wanted to be an actor before I was 18 I would have definitely tried to get into a drama school. I, however, was in my second year at university when I realized someone like myself could have a chance at becoming an actress. Nonetheless, after my first two professional acting jobs: Musical 'Oh What a Lovely War!' and feature film 'Le Fear II' I deiced that winging it as an actor was not good enough and I needed training asap. I had no audition technique and could not interpret a text or character very well. I was a mess in most audition rooms and this knocked my confidence. That was until I found my first part-time acting school Young Persons Theatre Company (YPTC). I then attended a course that was more screen-based: MN Academy. I am currently training at the Actors Cafe. I love to constantly be training as it boosts my confidence and keeps my spirits high!
How I got my first agent:
I read numerous articles on acting and attended several seminars and gathered that you need an agent to land screen jobs but to have an agent you need to have been seen on screen. Catch 22. I used my initiative and decided to audition for as many leading role parts in short films and indie projects. As soon as I was cast as a leading character I would then email agents, but they weren't interested as I did not have a showreel. I then made it my mission to get one made. I got my cameraman friend to record me improvising an emotional scene with my grandma! This little bit of footage got me seen for a lot more short film projects and indies. After a year of working, I gathered all my professional screen work together and edited it into one final showreel. Alas, I was finally the full package, I had a headshot, showreel and screen credits with part-time training under my belt too. I uploaded it to my Casting Call Pro profile and I was contacted by an agent within a few days and got signed!
Now I had an agent and was on Spotlight I felt invincible. Little did I know that was the beginning of a slow gut-wrenching process. I was lucky enough to have booked my first audition with the new agency; a featured role on a McDonald's commercial. But sadly the final edit had me blurred. This was heart breaking but I understood that it happens sometimes. After months of silence, I got a small part on Eastenders! I was the Olympic Torch Bearer with Billie Mitchel on the live episode. This opened so many more doors. As my credits grew I made the move to a top agent. I was then cast in Bridget Jones Baby, The Absolutely Fabulous Movie, Star Wars VII, BBC Doctors and Todd Margaret. Not all of which did I make the final edit, which is an example of how thick skinned you need to be in this industry.
My advice is to get some training and experience on set. Know your worth and keep going! Your big break could always be around the corner :D