All images should be 300dpi and Ideally in PDF format (bleed and tick marks preferred, but not essential) 

Alternatively we can also accept JPEG/TIFF/PNG at 300 dpi

There are many tutorials on YouTube to help with formatting your PDF with bleed and tick marks depending on what programme you are editing on.

Photoshop Bleed & Tick Mark Tutorial

Acrobat Bleed & Tick Mark Tutorial