Do you guys have any art tips that are really helpful...

As cliche as it may sound, just try not to overthink imperfections! Almost nobody will notice the minor issues and even less will care about them.

Think about minor imperfections obsessively. Never let a single problem go unchecked. 👍 

Don't stress over your sketches, and try to keep your hand a bit more loose than you would with lineart. It will likely reduce the risk of pain in the hands.