Bold, contrasting colors tend to work well. Text should be as large and emphasized as possible.

Any important text or design items should be at least 2mm from the edge of your sticker (3mm from the edge of your artwork).

CMYK 0-0-0-100 is sufficient for black. If a richer black is required, 20-20-20-100 or 50-0-0-100 is sufficient. Heavier blacks can be prone to flaking from the excess ink used.

CMYK colours cannot exceed 300% total, i.e. 70-70-70-100 is too high (70+70+70+100 = 310%). The drying time required for colours higher than 300% is prohibitive to a reasonable turnaround time.

dafont.com
Loads of free fonts

openclipart.org
Public domain clipart

istockphoto.com
Cheap, royalty free photos and illustrations

whatthefont.com / identifont.com
If you are trying to identify a font

commons.wikimedia.org
Public domain photos and illustrations

fromoldbooks.org
Public domain illustrations from old books

Stock.xchng
Free stock photos

Oliver Kontis Design
Andrew Design
Fragile Vision Design
Mads Designs
Greeno Media Solutions
Twisted Designz

Student Design
Kiss the Future Design
Rayman Designs
EmilyDesign
LookHappy Design
This is Design
Dinosaur Design
Biff Art

None of these designers work for us, we've only gathered these links to help you find one if you need one. We'll try to update it once in a while and would appreciate feedback if you use any of them, or use someone who isn't on here that you think we should add.