The Right to Keep and Bear Arms is guaranteed in the Bill of Rights. So is Freedom of the Press. We need to utilize the latter to promote the former.
Many newspapers have conditions on what letters they print, how often they print them, length requirements and restrictions, etc. In spite of that, Letters to the Editor can still be an effective way to get our word out to the public.
Make sure your submission uses correct grammar and is checked for spelling errors. Similar to speaking with legislators, stick to the facts. Emotions are the weapon of choice for the anti-gun crowd. Emotions cannot be backed up with varifiable facts. Keep your letter brief, concise, and topical.
Don't overlook publications other than newspapers. Magazines also usually provide space for feedback from subscribers. Iowa Carry members have had letters published in magazines produced by the NRA, for example.
Do not be discouraged if you letter does not get published. Editors have a tremendous amount of mail to go through, and only a small number of submissions ever get published. Keep making submissions, though, and if enough people write, eventually one (or a few) will get published.
You can easily send letters to the various media outlets in Iowa through the Iowa Carry Legislative Action Center.