Setting up files for printing ???'s

[kundalini]

I have some files I want to send to someone for printing. I don't print, so I'm not sure what to do. I'm guessing they will go to a walmart or similar printing service, but have no idea for sure. And I'm also guessing that 6x4 or 7x5 will be the print size. I'm going out of town and can't sort out prints before they leave out of town this coming week.

What should I consider to set the file parameters to before I send the files via e-mail?

Thanks for the help.