This is a very individual question and would need an extensive analysis of your current AdWords campaign, website and competitors.
We normally do not work solely with the intent to lower AdWords CPC, but we recognize that sometimes it’s the final goal.
You should be careful with focusing solely on how you can lower your CPC if you have a campaign that is converting well (bring in profits). Sometimes it is better to optimize your campaign’s conversion rate instead of solely focusing on lowering CPC.
Optimize for Profits – Not Solely Low CPCs
Truth be told it is not that hard to lower AdWords CPCs. You simply identify the keywords with the lowest competition and make sure you get the most traffic from these keywords.
Sounds simple, right? Then why aren’t more advertisers doing this?
The answer is money. Advertisers do not use most of the keywords that have a very low competition/CPC because the keywords aren’t profitable.
Sure, they have a low cost per click, but in the end you waste the money because these keywords don’t drive any profits.
This is why the most successful AdWords advertisers optimize their campaigns with the goal to increase the conversion rate, or profits, instead of solely focusing on the cost per click.