Phone the paper you are interested in, and ask for the Picture Desk - they will assess pretty quicly if they are interested or not. If they are, offer them 'First Use Rights' which means they can use them once, and then the copyright returns to you. Obtain copyright by posting a set of negatives to yourself by Registered Post, including a signed dated letter that confirms your ownership of the negatives, and don't open it on receipt. Advise the paper that you own copyright, and if they want to negotiate to buy it from you, be careful - if you reach that stage, contact an agent - The Writers and Publishers Yearbook at your local library will give you some addresses, and go from there. Good luck - and don't sign anything unless you are completely sure what it is.