However, in answer to your question, I would say to pick a subset of the options listed. Unless you are a very special person, you will not master all of those skills.
It really depends on what you are good at and what you love. I am a programmer and therefore the 'business' side of game programming is where I shine. Making the idea rise out of nothing. I am in awe of the creative side that supplies me with the pieces and parts to do so.
So I focus on the bottom part of Courtland's list - with one caveat. I love games. If you don't, don't start writing games for a living as there is more money elsewhere. It's cool as a hobby if you don't want to get serious.
The pieces you don't master can be supplied by others. I would love to be able to the graphics and I have done so, but when compared to the stuff available out there, very sad!
Tony recommends the following next steps:
- Decide what side of the process you want to focus on. Unless you are working alone and have no budget (a real tough road), the better you are on your skill set, the better the final product.
- Don't ever forget why you started - love of games. There will be times ...