Thanks for the links. It's always nice to see what other pixel artists are doing.
I've been wrestling with AA recently too. Here's what I've learned.
First up, do any AA work LAST. If you tweak your other colors at all you will have to redo the AA pixels and it is tiresome.
When to use AA?AA has trade-offs. On the one hand, it reduces the jaggies and smooths the curves. On the other hand, it blurs your image and effectively reduces the resolution. There doesn't seem to be any good rule of thumb for when to use it or not, but
1) You probably don't need it on straight lines that don't have any jaggies to begin with.
2) Avoid AA on small sprites. The smoothing is not worth the effective loss of resolution.
Which pixels to AA?Hopefully the more experienced folks can expand in this.
AA is slow if you do it by hand. So focus on areas where the pixels aren't already smooth, like where a line or color changes angle. Jaggies can usually be fixed by working on the underlying lines instead of using AA (it's faster that way too), but some areas will still have too sharp curves or banding.
If your art is going to be a sprite or be put on different backgrounds, then only AA the inside edges of the sprite. If the art is part of a piece with background and all, inside or outside is fine.
How to select the colors?If you have a limited color set, then you have to be very selective about using colors only for AA. I expect there are some tricks on how to choose colors that serve both as AA for two existing colors and as a color for other objects on the screen. I haven't seen any tutorials or tricks like this though.
If you don't have a color limit, then the AA methods are a variation on blurring or blending. I think most people try and judge it by eye, but I made a chart:
For a target pixel in the center (C), you blend with the surrounding colors. I list three different weights for the blending. They're based on different math for how to blend the pixels, but you can just use those numbers or use them as examples and make your own balance.
Hopefully this can help you get started.
Things I'm not sure about yet:
AA tends to smudge the picture, which should reduce the appearance of depth. But AA is often used on edges, where the depth changes significantly. These two effects should be in opposition, I'm not sure how they actually play together.
Tourist