I already do know what design to do for the poster, as well as the poster dimensions/size (I'm creating this for someone, and they already told me what size they wanted).
Since this is going to be printed, is there any other specifications that I must use/follow so that the poster wouldn't look bad/cropped when it's printed?
They told me that they'll be going to an actual printing store for the poster.
Do I use a 300px resolution?
Should I use margins and how wide should they be?
Is .jpeg the best file type to save it as?
Thank you!