What you write in your ad text is very important to success in AdWords campaigns. It is important to realize that you are not only competing for ad space based on your Max CPC bid, but you are also competing based on the effectiveness of your ads. AdWords uses Quality scores and ad formats along with your bids to determine ad rank. Your ad text must be compelling and extremely relevant or you will have to pay much higher click costs than your competitors.
Make sure that you use tightly focused keyword lists in your ad groups so you can write ads that are very specific to every keyword in the group. That means you will need lots of ad groups with short keyword lists and multiple ads written specifically for the keywords within each ad group. That usually means you will need to craft a lot of ads, typically 3 or 4 ads for every 5 to 10 keywords.
That can be a daunting task for a new advertiser so hiring an expert ad writer may be the right thing for some people. If you choose to do it yourself, make sure you take the time to do it right because it will cost you a great deal if it is not done right.
Also, bear in mind that your ads pay a crucial role in testing various selling points. You need to craft an ad that focuses on a single selling point. Craft multiple ads for each ad group, each focused on a different selling point. This allows you to gain valuable insights into which selling points work best for each market segment you are targeting. Without properly written ads, you will miss those valuable insights.