What job you’re working, esp. early on, matters little. What does matter is getting close to those who are working at what you’re interested in. I recommended an ad firm simply because they are way more common than animation studios. If you have an anim studio nearby, by all means, apply! (for anything!)
Remember, its mostly about developing relationships. The old phrase “Its not what you know, but who you know that counts” is very true! (Of course it helps to be very good at what you do, but if nobody that matters knows about you, then all that skill is for nought.)
Always be friendly, show interest in and go the extra mile to help out those who are doing a job similar to what you want to be doing (creating artwork at minimum, but hopefully someone animating!) Not only these folks, but also (and this is very important) their bosses! Never underestimate the power of brown-nosing the boss! Just be genuine, though. People are just people, no matter how lofty their role, and we all appreciate honest friendship.
Yes! Don’t stop creating. Doodle, sketch, sculpt… using pen, pencil, crayon, chalk, charcoal - whatever is at hand. And by all means finish what you start! (This has been one of my bigger challenges, since I tend to get bored easily and want to move on.) And remember to keep what you do filed/stored away for possible portfolio inclusion.
I think, in general, that success comes through being able to sell yourself with confidence. When someone asks “can you do that?” always say “Yes!” without hesitation, whether you know how to or not. Worry about how you’re going to pull it off after you get the “okay”. If you end up not being able to, then at least you learned a lot in the failure. Keep moving forward! 
The story that always sticks in my mind is that of Bill Gates and Steve Ballmer saying, “Sure, we can provide the OS for your IBM PC!” when they actually had no clue about operating systems. Once they got the sale, they went back to the shop and figured out how to pull it off (in this case, by buying an existing DOS from some dude for $50k.) The result? Micro$oft’s billions.