Good luck! For pixel art tips I would say:
1. Use color palletes from lospec! They make your pixel art look more unified and consistent. https://lospec.com/palette-list
2. Always use reference. Always. You can also use other people's art as a style reference if they are ok with that, as long as you don't steal/trace and claim it as your own.
3. The easiest way to make good pixel art is to use somebody else's good pixel art from open game art. Pixel art is really fun though, so I'd recommend at least trying it!