I suggest that you follow the design specifications for sticker printing in this article and use the required design software to ensure high-quality stickers. Take a look at the specifications mentioned below:  

Software Compatibility 

Adobe Illustrator is my favorite file format. If you're using some other program to create your stickers, please check with your customer service or sales representative to see if it's compatible.  

Make sure you're not using any page layout programs to type or layout your sticker. Instead, use Adobe Illustrator to set, type, and compose your artwork.

In Illustrator, set the form and compose the image. For the background picture, use Photoshop. The file must be in CMYK format with a resolution of at least 300 dots per inch. Make sure the PDF file settings have a thumbnail, as well as no color conversion passwords.  

Artwork Setup 

Often use the CMYK colorspace when creating label artwork. If the artwork is in RGB, you must convert it to CMYK and have the client accept the color change before submitting it to be printed.  

Send related files with your mark file at all times. Include both printer and computer fonts when using postscript fonts. For the small kind, I suggest sans serif font between 4.5 to 7pt.  

Make a point of converting all text to outlines. Quality sticker printing cannot be made from PNG or GIF files. It is strongly suggested that you use JPG formats.

JPG images must be in CMYK format with a minimum resolution of 300 DPI and no text; the JPG image can only be used as a backdrop for the original high-resolution file.