Generalities don't work. When you don't know what to put in the headline, go for a customer benefit. Telling what you do for people is much more powerful than telling them what a wonderful company you have. If you have better brands than your competitors, list them. And use their logos.
People often go to the YPs to find a dealer for something they already want.
Include the essential information. What you do, phone number, location, credit policy, price info, and your company name. Don't get fancy. Flowery words or type will only confuse people. The two most important elements in any YP ad are what you can do for people and your phone number.