Vector artwork is best if printing a logo or illustrated artwork. Vector files usally end in .AI .EPS .SVG or .PDF and offer the most accurate print results. You can test to see if a file is vector by zooming into the file and observing that all the lines stay 100% sharp without any pixelation even at extreme zoom levels. High resolution files are ok when vector is not available for images like photos and full CMYK artwork. High resolution files should be 300DPI and as large as the actual desired print size.