Really thankful for this tutorial - I'm glad to know that there are certain techniques for pixel art. 'cos the general impression I got from reading pixel art tutorials on the internet, make it seem like some kind of magic where you'd had to feel for everything. At least with your tutorial, I know now to pay more attention to HSV haha..
Of course there are techniques. There are lots of different technique, by far too much to cover them all. I think the only things you have to feel is are the fine nuances of the feeling you try to transport with your pieces works. Maybe it's also possible to exactly plan this, but at the moment it's one of the few things I am using more the try&error way instead of a fundamental knowledge.
Fantastic tutorial! Incidentally I was making some treasure chests today using these exact methods. I personally don't like to go a step farther with the high detail, but like to stay a step before that so that the tiles are easier to make. Also, I like to sprite in 24x24 (Like Kirby Super Star) because for me, it's a good balance between ease-of-drawing and detail. I suggest you give a little mention to 24x24 resolutions because they work great for me. I think I draw in 45 oblique angle...I might experiment with some other angles.
24x24px resolution is something really uncommon and don't really works well for all games, especially not for RPGs-like games. The secret about this is the size of the charakters. If the characters are too small (not recognizable) or to big (claustrophobic feel) in a game you have a serious problem. In the case of your SNES kirby game it worked pretty well because most of the dreamland characters are just enhanced spheres and if you compare it with other char-sizes they have a nice size. If you'd trace the general proportions of a 16x16 char to 24x24 tiles and keep the screen resolution the char will be to big, if you use a 640x480 res the 24x24 char looks pretty small. Ease of drawing and detail of this resolution is pretty unimportant because you don't have a related screen resolution. If they work good for you it's one thing, but I won't say it's general an established resolution and if it comes to this tutorial it's possible to derivate the advantages and disadvantages, except this very important point I just said you.
Another thing I have to mention: the SNES used 8x8 tiles, but most games are done with 16x16 metatiles. Metatiles are just tiley which contains other tiles. THe GBA also uses a pretty similar tiling system as the SNES. The thing about the metatiles is that it saves lots of time to create less but bigger tiles and well made bigger tiles look as nice as lots of small tiles. YOu also save lots of time for creating maps with bigger time and time is a very important factor, especially if it comes to commercial art.
If you want some more in depth informations, or something isn't clear just ask - I don't know how much I'll mention about this. I think it's better to cover the most important things in these tuts instead of talking about pretty in-detail stuff which maybe nobody ever need to know. It's hard enough to keep the tuts short and clear just with the very-basics
(Late reply as I'm a bit inactive on dA now) Thanks for the pointers! Much appreciated! My project has a screen resolution of 256x224 and characters based around a 24x24 tileset. I do understand your explanation and agree with you, but there shouldn't be any more of a problem with cramping because my sprites are proportioned the same as Kirby Super Star sprites, just with a little less leak onto adjacent tiles.