Please Check the following before giving the job:
File Format:Corel Draw file (Any Version) are most preferable.
All Fonts must be converted to curve,for maximum quality do not give BITMAP file (i.e JPEG & TIFF)
Color Format Artwork should be in CMYK mode,Avoid using 4-color shade (e.g C65,M70,Y35,K30) nas this may result in patchyness color variation.
Do not use spot colors (i.e Pantone) & Registration (C100, M100,Y100, K100) Do Not Use Scale With Image in Outline & Always Use Behind Fill in Outline