The absolute best thing that you can do is not concern yourself with keyword density and instead write for humans.

The best keyword density is the most natural sounding. If you're trying to rank for the keyword "red shoes" then if you had sentences all over your site like, "If you are looking for red shoes and not blue shoes but red shoes then you've come to the right place. We're the best place for red shoes that you can find. So to find red shoes just click on the navigation menu."

The keyword density there would be way too high. Repeating your keywords in an unnatural way is too much.

Keyword density is important to your ranking ... it's important to make it natural.

Keyword density is important, but like dani said, write for readers.

Search engines will detect how many times the term is displayed on a page, and it will dynamically affect your ranking positively, up to a certain point. After a certain amount of times they keywords are said, it begins to look like spam and is affected so.

Keyword density is important to your ranking . it is a factor as to determine a webpage whether it is relevant to a specific keywords.

As far as search engines are concerned, if a particular keyword has a higher density on that particular web page, then the chances of that page obtaining a much better search engine ranking increases almost exponentially. Not all search engines compute or evaluate keyword density in the same way and most have their own proprietary algorithm for calculating the average density of a keyword.

But that only works up to a point, at which time the curve takes a sharp downhill turn.

I did some research on this recently and most copywriters say keep keyword density under 10%, just make sure your h1/titles/h2 are targeting the keyphrases, and maybe have the keyphrase repeat a few times througout the page.
Keyword density used to be much more important with seo but I rewrote some content to have less keyword density and my sites are ranking better, especially on the new live search.

if i say simple never repeat the same keyword lots of time. Just right your copy so that the keywords are neither less nor too much.

Again quality is important, if you focus more on highly effective keywords that will worth much more, don't bother about density.

Keyword density is important as per the latest update of google.but donot stuff it with keyword as google is taking measure to find website thats specially/artificially made for that keyword .So if you are targetting a keyword for your website,then use the following method to know the recomended density for that particular keyword..which i discussed in one of my previous reply..
To measure the keyword density and to low down/increase the density,we should first take in consider which keyword you are targeting and for which search engine TLD you need to do the seo .TLD means top level domain like .com,.co.in,.co.uk etc

for example if you are targeting a keyword "top resorts in kerala" and as the location kerala is in India,you have to open google.co.in and search the keyword in the search bar and get the first 10 results.

Note:there are many sections in SEO we need to takecare of the keyword density for a particular keyword

For the time being,we will talk about the title as a start up which is seen in <title></title> tag

Analyze all the 10 top listed websites title and check the maximum times they used the keyword.

like site#1 kept -cheap resorts in kerala
site#2 kept -best resort in india
Site#3 kept -affordable resort in cochin and so on..

then for the keyword -top resorts in kerala,you should use the following density

The "top" didnt used at all in the above sites,so you should keep it atleast once..its recommended.
The "resorts" used 3 times,so you can use the keyword "resort" atleast once and maximum 3 times.if you didnt use it for atleast once then keyword density of the word 'resort' inthe keyword-top resorts in kerala for the title tag is low and if you use it more than 3 times then the keyword density is high.

the "kerala" used one time in the above sites,so you can use it for atleast one time and maximum one time only

So by analysing like this,your title for the keyword"top resorts in kerala" can be some ting like this

example title:"top resorts in kerala|Best resorts in India|cheap resorts"

this is achieved by using the above method
using top atleast once (recommended for keyword:top resorts in kerala)
using resort for 1-3 times
using kerala for definitely once

hope this helps..
let me know if you need any clarification.

Thanks

Mark