As much as I enjoy being a pixel artist, when it's client work I will be charging a small fee per asset. You might want to consider that first. I usually charge around 10-20 for most simple sprites but it also depends on how much animation there is. Larger tasks such as environments have to be negotiated and broken down into smaller steps before I set a price. Just letting you know ahead of time. I'm always willing to cooperate with the artwork if it needs revision though so you will get what you ask for.
On the other hand, If you're just wanting to learn to do your own art for your games though, I highly encourage that and can try to teach you.
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