Following on from HannahS' excellent post about PPC, I wanted to add a couple of points I had recently discovered. I will not focus on keyword competitors in this post, and some of it is theoretical, without tangible proof, but it works for me and thought I would share it.

• Firstly, duplicate keywords in your Adwords accounts are considered a bad thing, as in theory they will only trigger one advert, and normally only trigger the advert from the ad group which is performing the best. However, by using duplicate keywords you can actually help reduce your keyword costs, and further improve the value and perhaps relevance of your PPC campaigns.
• Secondly, my previous experience in reducing keyword costs has mainly related to keyword relevance in both advert and landing page.

Anyone using Adwords should always be using the Adwords Editor as a way to help organise and diagnose issues with your campaigns. One great feature available with the Editor that isn't readily available with Adwords (or I haven't found it yet) is the duplicate keywords tool. This tool is pretty self explanatory -- it gives you a list of duplicate keywords either in ad groups, campaigns, or across multiple campaigns. 

Obviously, once again these are duplicate keywords, each of which I could be bidding on; however, let me please draw your attentions to the right hand side of the column which highlights the difference in price for each keyword. Pretty much every single duplication here presents 2 prices for each keyword/phrase. Some are only a slight difference in price, whilst the "playstation 3 vs xbox 360" represents a major difference of $0.32 for the duplicate keywords.

All the ad groups are short and highly relevant, and each contains adverts which, again, push the relevance factor; however, obviously there are subtle differences in the groups which are reflected in the prices above. This was all well and good, until I noticed something with some of the keywords, something (theoretical) which must have had an influencing factor on the prices.

In some cases, the duplicate keywords had the SAME advert, and pointed to the same LANDING PAGE, 2 of the main factors in determining a keyword quality in adwords. So something else must have been influencing those price factors.

The only other factor I can see which was affecting the ads was the actual name of the ad groups themselves. This was not consistently the case, and it may be just pure speculation on my behalf to suggest that naming of ad groups would alter the cost per click of keywords.

Putting that point aside, at least using the Adwords Editor has allowed me to really refine some keyword costings without sacrificing performance. If anything, it's enhancing performance.