It may sound somewhat irrational, but I suggest finding more reference pics, from different angles if you can (this should be obvious, but the higher the quality, the better). It can help make finding little details much easier. Obviously you won't be able to put in every single detail on small sprite like that, but it doesn't hurt to add a little more detail.

But for a first attempt, it is not bad at all. Sorry if I sounded nitpicky.