Setting and adjusting keyword level bids
In addition to being able to set ad group level bids, which apply to all keywords within an ad group, you can also set keyword level bids. Individual keywords within an ad group will perform differently, and you'll want to consider increasing bids for low position keywords or decreasing max CPCs for keywords that are not profitable.
Getting ready
Before you adjust bids, research keyword performance. Pay special attention to the following keywords:
Costly keywords with no conversions or few conversions: Decrease bids for keywords that you are spending money on but that are not converting. For example, with a target CPA of $10, decrease bids on keywords that are generating conversions at a $15 CPA.
Keywords below first page bid: Consider increasing bids on keywords that are not shown on the first page of Google's search results.
Cost effective keywords: Increase bids for keywords that are generating profitable conversions to boost ad rank and get more...