@yaomon17 sound advice but not the best example I'm afraid

@OP reduce some of the superfluous colours, and light it from one side to emphasize the edge works well, also bring the handle width in, and maybe extend the handle a little bit.

I don't think the lamp post or chest work very well, the lamp is just too big and the details don't harmonize design wise, so it's more design than it is pixel technique.
the chest, you'd be better to reduce the colours a lot, and to seperate the lid from the base, here's an example

the cactus however works really well in terms of detail and readability,
I'd suggest focusing on the lower resolution pieces, with more of a game art focus
