People have taken a number of approaches trying to do their own advertising ranging from silly all the way to insulting. These people choose there approach for various reasons. Some were ignorant about advertising and marketing while others were acting on incorrect information - usually in the form of cliches such as "sex sells." If you're in doubt, I can assure you that unless your business is in Nevada, sex does not sell. If you're going to handle your own advertising, here are a few things to avoid:
Pictures that have nothing to do with your product or service - If your company is in the carpet cleaning business there is no reason to have a picture of a baby. No one is going to say "What a cute baby, I think I want this company to clean my carpets." The same goes for pictures of sexy people (male or female) in provocative poses and little clothing.
Cheesy headlines - I actually saw an ad with a headline that said "We might be able to afford a bigger ad if you'd buy something from us." Yes, this will probably get someone's attention, but do you want to be remembered as the company that is having financial problems?
Illegible fonts - Most people will not take the time to decipher your ad when it is written in brush script, in which case, even the most persuasive copy is rendered useless. You want to use simple, clean fonts for headlines and body copy. Save the artistic fonts for accents and things of that nature.