When creating Keywords, keep in mind that Keywords tell the search engines when to show your Ads.  This is essentially how you reach your target audience.  The better and more targeted your Keywords are towards your products and services, the better your conversion rate will be. 

When you're creating Keywords, via the Create new Keywords flow, there is a "Suggest Keyword" button that can help you think of popular keywords if you are stumped.  This Keyword Suggestion tool is very helpful.  It will not only return popular Keywords based on the Keyword you entered, but it will also show the Advertiser Competition and Average Search Volume per Keyword.

Advertiser Competition gives you a gauge on how many other advertisers - like you - are placing PPC Ads for this keyword.   Average Search Volume shows how many people are searching for that keyword on a global basis per month.