I don't really know anything about this, so please excuse my stupid questions.
I want to create a document in Affinity Photo that I will send to a printing company to be printed as a poster. The size of the final print will be 18 inches by 24 inches. So, how should I set up the document. I think I should set the color mode to CMYK and the dpi to 300, but that's about all I know. What should all the other settings be set to ?
Also, what size should I make the document ? Does the document in AP actually have to be 18" x 24". When I try a document that size my AP seems to start lagging a little, especially if I'm using a larger brush (I don't know if it's just my computer or AP). If I made the AP document half-sized (9" x 12") or even one-fourth sized (4.5" x 6") while I work on it and then resize it to full size (18" x 24") to export it, would that have a negative effect on the quality of the final print ?
Finally, unless the printing company specifies a certain file type, what is the best file type to export the document in ?
I appreciate any help that anybody can give me.
Thanks...