Title, then h1 h2 h3 tags, then the first line of your content and the last line. (guessing you are speaking from an admin point of view)
Right, all above... one more to add >> use them as anchor text for internal linking and while getting backlinks from other website. Make sure you don't spam or stuff them unnecessary.
First off, you need to take care of the <head> section of your web page. This contains the: Title Tag: Include your keywords and separate them with hyphens (-). Put your main keyword first because order has weight. Meta Keywords Tag: Even though this tag isn't used by major search engines for ranking, some minor ones still use it for rankings. Include all your keywords in it. Meta Description Tag: This tag has no ranking power what so ever. However, it is the first description a user will get of your website when you first appear as a SERP. It is important to have a short, precise, and attractive description of your web page because this could easily increase your click-through-rate. After that, you gotta make sure your URL is properly optimized. Keyword Placement: Place your keywords the closest possible to your domain name. Try eliminating the most subfolders you can. URL Lenght: Try keeping your URL the shortest possible also by eliminating the most subfolders possible. Keyword Separators: I recommend using hyphens (-) only to separate your keywords. Unlike the underscore or commas, hyphens are seen by search engines as word separators. Now comes the optimization of your <body> tag. In other words, your content. Keyword Repetition: It is good to repeat your keywords a few times throughout your text. Note that repetition of keywords is good, not spamming of keywords. Look as natural as possible. Remember that you are writing for people to read your content, not only search engines. A stuffed keyword text is very heavy and boring to read. Keyword Variation: Use a variation or combination of keywords or key phrases. This helps for your rankings of long-tail keywords. Keyword Density: A lot of myths revolve around keyword density. Some say it is important, others say it is a total myth and waste of time. I am still going to put it in here though. Your keyword density should stay between 2% - 5%. There are many tools out there to calculate your keyword density but if you cannot find any simply add up the total number of words in your content and divide your keywords by that total amount, multiply it by 100 and you have your keyword density. Headlines: You should use the <h1>, <h2>, <h3> tag in your content. Don't use anything lower because it has no ranking weight. Include your main heading (containing your main keyword or key phrase) in the <h1> tag, use it only once per page, and put it at the top of the page. Remember that order has weight. For any subheadings, use the <h2> tag, and for sub-subheadings, use the <h3> tag. Images: We all know that search engines don't have eyes so they cannot see any images. To make those images visible to the search engines, you must include a title to the image, a caption, and an ALT tag all containing keywords. You should save your image file name as keywords as well. Bold: Putting words in bold in your content will tell the search engines that these words are important, therefore it is best to bold your keywords in your content's text. I hope I gave you a good head start of what you need to know about how to optimize your keywords for your on-page optimization. Obviously there a few more things but the important stuff is here. Do some more research on Google for On-Page Optimization. If you have any more questions, ask away !
@ metaseo Does it ok to mention the keyword in the article for 2%-3% for to get optimize the article for SEO to get enough traffic from search engines. Or it will be held to be as a keyword spamming. I posted an article which contains 546 words and have upto 5 paragraphs. I used to mention the keyword 1-3 times in every paragraph and in h2 tag and over all i kept it upto 16 times to appear in the article except title and header tags. I only use one header tag at starting of article. Does it ok for optimization of an article. or it comes under the keyword spamming. Suggest me in the right way.. so that I will forward to next step.
Like I said keyword density is believed to be a myth but you shouldn't worry too much about it. Try to make your text look as natural as possible. Read it over and see if the text sounds good the way it is. If yes, leave it the way it is. However if you find it to heavy or boring to read because there is too many keywords, then just erase a few. If you do not want to erase them, change them by using a variation or combination of keywords. If you wish, you could send me your article's link and I will read it over and try to help you out.
Use them in all the right places. Use your keyword in the right places like title, description, header tags, anchor text and alt text (if you have images). Build links from sites with high PR and focus on quality rather than quantity. That should really get you going.