I started doing computer graphics in the mid 80s, and after all these years, there are three things I believe you need to succeed.
1) Imagination
2) Ability
3) The patience of a saint
The first will let you come up with the ideas. The second will let you translate those ideas into actual content. The third will stop you killing the client, after the 15th time of them saying "Oh, that's not quite what we wanted, we actually meant this..."
I remember working on a fighting game in the late 80s, and the client came round and said "We want him to move like Bruce Lee". So I copied Bruce Lee's actual moves from film, and they said it was wrong... go figure. It got to the point, where they would request a change, we would leave it a few days, then send them the exact same graphics, and they would frequently say "That's much better".
Doing design for yourself is one thing, but doing commercial design to a client's specifications, is a whole other ball-game. It will quite literally, drive you insane. And if you get a tosspot creative director in the middle, things will get 10x worse. The client will tell the CD one thing, the CD will decide to tell you their version of that request, and when the client doesn't like it, the CD will blame you for interpreting it wrong... and if you get it spot on, the CD will take all the credit.
Which actually reminds me one more thing you need to get used to, and that's being told that the best thing you think you've ever done, is "just not good enough". Being a creative professional is physically easy, but mentally tough... but ultimately highly rewarding.