How can I have well qualified artwork files?   For Sail banners ,teardrop banners    
1) First of all, Download the Template form the product webpage, on the lright under the product photos. 2) Forward the template to your designer, or read the requirement carefully if you develop it by yourself.
3) ALWAYS use high quality, high resolution Logo files  or photos/pictures when you develop the artwork files, the higher quality, the better banner looks.
4) KEEP DESIGN SIMPLE. Usually People Only have seconds to look at banners when they are in motion, simple and impact goes a long way for banners.