Stoics believe in the four cardinal virtues: courage, justice, wisdom, and moderation. I think they're a good starting point for character development, and a lifetime of work on their own.
Probably the most efficient way is to study "good" authors, and to emulate "good" models of virtue. The second section of OP already gives some practical tips:
> A good character can handle emotions properly.
> We do that by finding the right mean between two extremes:
> Courage is the right mean between cowardice and recklessness.
> Temperance is the right mean between gluttony and abstinence.
Different "good" models of virtue will often independently reach similar conclusions: handling of emotions is notoriously valued in Buddhism; avoiding extremes is close to Confucius's doctrine of the mean[0], of which Jesus's "turning the other cheek" could be one practical implementation.
I can get angry at the drop of a hat, and I may be in the right, but my anger may not be proportionate. So for me, the action is to say sorry and explain what else happened that annoyed me. Also, it pays to fix or accept whatever made me angry.
Character is not purely an internal thing, but rather something that is built through your interactions in your environment, especially with people.
A better character is built by doing things that are challenging.
All those times you are confronted with choices that boil down to "I should do this, but I want to do that..."
Do what you should do.
Many or most of our choices that matter are that simple, but we work really hard to confuse ourselves, to justify and rationalize the choice we want, because that's what we want.
If our choices are difficult because it really is honestly difficult to tell what the right thing is, then it's not a moral flaw to be mistaken.
Nope, not what I was saying. I'm saying that distinguishing right from wrong is usually the easy part of the process. It's the 'draw two circles' step.
Not deceiving yourself about the result is the hard part. That's a psychological problem, not a philosophical problem.
Cool. So, then I just draw the rest of the owl? I have no idea where to begin to develop my character.