Hitwise’s Heather Hopkins has posted an interesting article about the mix of paid and organic search traffic going to websites, and the right balance to be struck between the two.

The post looks at the data for the top 10 Insurance and Appliances and Electronics websites in February, based on share of UK Internet visits.

The figures reveal a wide variety in the percentage of visits from paid search – varying from as low as 5% of traffic for Bupa, to 57% for Churchill Insurance.

Direct competitors have very different paid search strategies. For instance, in the electronics sector, Curry’s received 50% of its traffic from paid listings, while rival retailer Comet received only 18%.

In the insurance sector, both Churchill and Confused.com received high percentages of traffic from paid search, 57% and 56% respectively. In these two cases, the high percentages are most likely a result of the competition for keywords in the insurance sector.

In insurance, rival companies are competing for a limited number of keywords. For instance, the top term, ‘car insurance’ accounts for 29.29% of searches for that product in February.

Figures from an earlier Hitwise post show that paid search isn’t essential for every kind of website. Leading sites like the BBC, MySpace and Bebo all receive less then 1% of traffic from paid listings.

However, in the case of e-commerce websites, the big players tend to spend money on paid search. Amazon and eBay, two of the biggest names in e-commerce, received 13% and 37% of traffic respectively from paid search.

So what is the best blend of paid and organic search marketing?

There is no easy answer; it can depend on what works for you, so it is essential to continually adjust and test your campaigns to achieve the best return on investment.