You send them the full size picture without watermark. JPG compressed so its not too big.. 2500pixels at longest side and no bigger than say 1.5mb
You put all your details in the exif iptc ... a caption stating whats in the picture, where and when.. you then include all your details contact and payemt.. i put my bank transfer details in.. I also put a note saying no free usage.. if all that is in the pictures exif then you send it off with a brief explanation in the email
I would reccomend you tell them you accept there standard rates so long as not free
then sit back and wait.. If you do the above then no paper would use them pretending they didnt know... your covered to send them an invoice if they do... if your picture is used send a confirmation email then wait anyhting up to three months to get paid