Title Tag This tag should contain your most important keyword phrase. Make the title interesting enough to grab the visitor's attention. Only use 5 to 6 words in your title with your most relevant keyword in the beginning.
your keyword should not increase more then 5% of your article length. So for a 100 word article you can use your keyword 5 times. Though personally I try to keep it as low as between 3%-5%.Overdoing of keywords makes Google bots realize that you are spamming your post for particular keyword. Google penalize such post and related post. Spider will think that you are trying to trick the system by putting up lots of keywords many times. This might affect your ranking. So be wise when you select the number of keywords selecting for SEO.
true, but don't overdo it. If you're blogging, try the free seopressor clone from bloggerhigh.com which will show you what sort of percentage you need for successful onpage seo.