Go with your gut and narrow down on a company that is prompt to respond to your enquiry, can provide useful information regarding the PPC advertising plan they can offer you, show measurable results and a client portfolio to verify their claims of helping achieve a high site ranking.
A good PPC advertising campaign should ideally help you attain high exposure for your website's products and services and use advanced and affordable SEO methods for obtaining top search engine ranking.
Additionally, the best SEO firm is one which will offer you a comprehensive web marketing service, not cater to just a particular niche online marketing strategy by ensuring you can measure results for website traffic improving and thereby, improvement in web sales too.
Thus, looking for a great ROI - return on investment - is what should guide your choice of a reliable SEO firm, who can ensure you get what you pay for in your efforts for top search engine placement.
Remember to ask about Google AdWords in your PPC advertising campaign as this method provides a fast way of getting your website advert on the search engines' first page using popular keyword research.
Consequently, for this paid SEO method for proven Internet marketing success, you as the website owner will need to pay the service provider for each click generated by visitors to your website.
This works best if you employ a reliable SEO firm for utilizing ethical PPC advertising while working within a specific budget that you set and if you can monitor your website account for clicks that generate in sales, because sometimes clicks can sure add up fast.
(So can your bill for the PPC advertising program! So, pick an honest SEO company).