They all go hand in hand - personally light source isn't much of an issue as it only takes about a second to work out, however as for palette it requires a lot more thinking. Blending - again is reliant on the palette.
It may not necessarily be the 16 bit console era anymore, but spriters are in high demand for handheld games - maybe not on the DS, but with mobile games and the like.
It's easy to think that a big palette can be a good thing, but thinking about creating a big game - it's best to use a relatively simple palette in order to tie everything up. It's all about balance and consistency.
Overall it's just something to bear in mind, if you work with the minimum - then you may have space to incorporate more things.