Always do a test print. Or several. I wasn’t able to get into the computer labs at school, and learned that the hard way. My ad came out a black muddy mess.
I got a B+ still, mainly because the professor liked the idea, the image, and the fact that I took the initiative to take my own photo instead of pulling one off the web. SO luckily, it pulled my grade up, because that print was horrendous.
Here’s the final ad, in color, the way I intended it to look before the printer got it.