I usually aim for 2-5% for any main keywords I'm aiming for. However, as others have said, it isn't all that important. If you want to rank highly, the best thing you can do is get backlinks to your site using your keywords as anchor text. That's how you really get Google to like you. Having the keywords in the TLD and under Title headings are also more important than having a good keyword density.
Be sure to have made a rich-content posts of at least 300-500 words per page. Insert your keyword these areas: TITLE HEADER FIRST PARAGRAPH LAST PARAGRAPH As long as your post makes sense, you don't have to worry a thing... keyword density depends on how short or long your article will be.
Every hundred words put one keyword. This was suggestion of 30 Day Chalenge course from last year. Use synonyms otherwise. Put KW in T1,H1 or H2 or H3, in description and in the URL - (onsite SEO) All the rest are back links (offsite SEO)
Avoid redundancy. You'll know to yourself if you have used too much of your keyword. Look for synonyms to make it look professional for both man and google bots.
Suppose a 500 words of contain so after each 100 words we have to put 1 key word, how it would be effect if cant arrange like this ..or through it we get only 1% density is it good?