You may be ranking organically for some of your keywords but would it be more beneficial to use the same terms for paid search as well? Since the effectiveness of your ranking keywords has already been proven, it might be a good idea to try if using them for paid search would yield even better results.
To determine whether or not you should use your organic keywords for PPC, you would need to compare traffic information for those specific keywords when doing only organic search campaigns and with traffic information when both PPC and SEO are implemented.
With a simple test, you can identify which keywords to choose for PPC as well as search engine optimisation. First you must go through your organic results and choose a term you rank number one in and add it to your paid search as a negative value to prevent your ad from appearing for those searches. Observe the results for one week. The next week, bid on that same keyword and observe for another week. Gather the data and compare the traffic from paid results versus organic referrals.
Depending on your budget, you may run the tests from as short as a week to a couple of months. Obviously, you can make a more accurate decision with more data on hand, but even a short study can provide you with useful information.
Aside from traffic, it would be vital to measure and compare conversion rates for each of these types of traffic as well. If upon analyzing the data for both types of campaigns you see that the SEO+PPC campaign produces more revenue than purely SEO, then it would be wise to bid on that particular keyword. Not all top ranking keywords are suitable for PPC though. Use only high converting keywords as the goal of the PPC is conversion and not merely click-throughs.
Also, the importance of a focused landing page cannot be stressed enough. Each keyword must have a corresponding landing page with a call to action, to allow easier monitoring of conversions.
While it is a common notion that using the same keywords for both the SEO campaign and PPC will cannibalize your clicks, the simple test will be able to determine if bidding for your top keywords can drive more traffic to your site. By comparing all data, it would be natural to see some cannibalization but it is crucial to consider the actual revenue made from PPC+SEO after subtracting click costs. In some cases, PPCS + SEO generate more profits even after paying for PPC, making the use of the keywords in both PPC and organic search worthwhile.
It is sometimes worth paying for keywords that you are already ranking for organically. The key is in identifying which keywords would give the highest profits when implemented in simultaneous organic search and paid search campaigns. Do not leave your decision to guesswork though. Investing a bit of time and a part of your budget on simple tests can save you valuable resources in the long run.
