Start with the finished size
Build the file at the exact trim size, which is the size of the finished piece after cutting. Use metric paper sizes such as A4, A3 and A5, not US sizes. One Australian printer notes that a business card here is 90 x 55mm, so a US template will not fit.
Ask the printer for a template if it offers one. It shows the trim line, the bleed and the safe area already marked. That saves guesswork before you add a single design element.
Add 3mm of bleed
Bleed is extra artwork that runs past the trim line. The printer cuts it off. Without it, you risk a thin white edge on the finished piece.
The reason is simple. Cutting machines are never perfect to the millimetre, so a cut that lands slightly inside the artwork shows paper instead of colour. Two Australian printers ask for 3mm of bleed on each edge.
Anything that touches the edge must be stretched out into the bleed. In Canva, switch on the print bleed view before you start. Use the background tool, not a picture, so the colour fills the bleed area as well.
Large signs can differ, so check the printer's own page. The printer's instructions always come first.
Keep text inside the safe area
The safe area is a margin inside the trim line. Keep text, logos and anything important inside it. A common margin is 3mm from the trimmed edge on each side.
One Australian printer explains why. Guillotine cutting can vary by 1 to 2mm, so a logo placed right on the edge may lose a corner. The same printer suggests avoiding thin borders near the edge, because it is very hard to cut them perfectly even. A border that looks balanced on screen can look lopsided in print.
Use CMYK, not RGB
Screens make colour with red, green and blue light, called RGB. Presses use cyan, magenta, yellow and black ink, called CMYK. If you send RGB, the printer has to convert it, and the colours can shift. Bright screen colours often turn duller on paper.
Adobe's own Photoshop help says to use CMYK mode for images in a full-colour print brochure and RGB for web or email. So choose CMYK when you create the file, not at the end.
Two other colour tips from printers help. Do not use Pantone or spot colours unless you were quoted for them. For solid black areas, one printer suggests a rich black of C60 M50 Y50 K100. Small text should be 100 percent black only (C0 M0 Y0 K100) so it stays crisp.
Check image resolution
Resolution is the number of pixels packed into each inch of a printed image. More pixels per inch means a sharper print. Screens show images well at 72 dpi, but print needs more.
The usual target is 300 dpi at the size the image will print. One Australian printer says 150 dpi is the minimum and 300 dpi gives the best result. Another asks for 300 dpi for images and 600 dpi for text based artwork. Vector artwork, such as logos, stays sharp at any size, so use vectors for logos and line art where you can.
Do not stretch a small picture to fill a big space. Making a file bigger on screen does not add real detail. If the photo is too small, find a larger original.
Export a clean PDF
Send a PDF, not a loose image. Printers say image files print at lower quality and cannot be edited. Convert text to outlines so a missing font cannot change your layout.
Export one page per sheet, not spreads, unless told otherwise. For booklets, the page count usually needs to be a multiple of 4 when they are saddle stitched. Crop marks are not needed at one printer but are requested at another, so check first.
Last, open the exported PDF and look at it at full size. Check the edges, the text and the colours. Ask the printer for a proof when colour matters.