Spray the newspaper with an alcohol-based deacidification spray, which you can buy from most scrapbook or art stores. Its restoration properties are limited at best, but it should help preserve the paper for a period of seven to 10 years, after which you can reapply the spray. Make sure you do this in a well-ventilated area. Stay away from the Sunday comics, as the deacidification spray tampers with colored inks.
Coat the newspaper lightly with a solution of milk of magnesia and club soda, which works to neutralize the acids in the paper and the ink. If you notice any further discoloration, stop immediately. Don't use bleach or any other chemical compounds.
Store your newspaper in a controlled temperature and humidity environment (right around 65 degrees and 40 to 50 percent humidity). Acid-free boxes work well, and don't expose the papers to direct sunlight. If you have clippings, try storing them in polyester photograph sleeves or encapsulation envelops rather than gluing them into a scrapbook. Make photocopies of the paper to avoid day-to-day handling of the original.