This is a good article. I might add a few more items:
6. Negotiate. Spot prices are often not set in stone, so sometimes you can request a lower price or sweeteners thrown in (like additional airings or a discount when running on multiple affiliated stations).
7. Analyze Your Results. Ask customers how they heard about you when they checkout. See how radio compares to other ad formats you use. See how one type of radio spot compares to another type (maybe a soft sell vs a hard sell). Continue the spots that give better return on investment (ROI).
8. Consider Shorter Spots. Often this is not worth it, but it is at least worth exploring. Standard radio spots are usually 60 second, but stations also sell 30 second spots and other time amounts. If there is a decent discount on these different time amounts, then it could be worth your while to run more spots with shorter times - especially if your message is short and sweet, not requiring lots of explanation time.
David Rodgers, Jingle Composer, DoctorJingles.com
Maximizing Radio and TV Ad Dollars With Catchy Jingles