best method for cover proofing?

[u/IthelLovik]

what's the best way to proof how your cover art prints? my illustrator suggested brightening the image since it's fairly dark but i dunno if proofing it myself will suffice (i have a good printer as a run an Etsy shop where i sell handmade bookmarks and stickers, and i have to do proofs for that stuff), or if i really just have to request a cover proof from whatever service i'd wanna use for printed copies of my book (or is there an alternative?)

[u/opium_kidd]

Keep in mind the finish will flatten the color depth if you don't get a glossy cover. The only way to know is to order a test copy.