If you're looking to prepare vector art for screen printing, there are a few key steps you should follow to that your design comes out looking exactly as you intended. First and foremost, it's important to create your design in a vector-based software like Adobe Illustrator or Corel Draw. This will allow you to create crisp, clean lines that will translate well to the printing process. 

To avoid any font issues, it's also a good idea to convert all text to outlines before saving your file.

Finally, when saving your file be sure to save it as an EPS or PDF with all layers flattened, as this will ensure that your file is print-ready and ready to go.

By following these steps, you'll be well on your way to creating a print-ready vector art file that's perfect for screen printing.