Keywords are the fundamental building blocks of any paid search account. When you first launch a PPC account you will always have a list of keywords. It is crucial that you continue to find and develop new keywords so your account can grow and maximize impressions.
There are 2 approaches to keyword development: 1) Proactive 2) Reactive. Whilst we would all love to be proactive all of the time, being reactive is also necessary in order to understand the marketplace and make adjustments accordingly.