Do a test print!
Print a color 8 ½ x 11" draft of your poster. This draft will help you find errors and assess the layout, colors, fonts and graphics of your poster.
Ask a friend or colleague to review the content and design of your poster.
Confirm the size parameters for your poster
Hopefully, you did this before you started making your poster. However, it is a good idea to verify the dimensions of your poster prior to sending it to the printer.
Save your poster in the appropriate file format
Save your poster in the format of the design program that you used (.indd, .pub, .pptx) and as a PDF.
Your printer may prefer a PDF file, and conference organizers often require presenters to submit a PDF of their poster prior to the event.