Keywords throughout site or per page?

Hi there, first time poster here so be gentle!

I've been researching SEO for a little while now and am getting a hang on it, and I understand its beneficial to make each page optimised seperately, but if one page is quite similiar to another and covers similar areas, is optimising the texts for the same keywords going to do anything for the site's ranking?

I suppose what I'm asking is - to use an example - if I run a site selling used cars, is optimising each page for the words "used cars" (as well as others more specific to the page) going to reinforce the whole site in Google, or just ensure that my pages are competing with each other?

Thanks - and sorry if its been posted before... I had a quick browse, and tried searching, but couldn't think of any search terms that would definitely nail this!

The site has a theme - "Used Cars Toad Suck, Arkansas" (actual place), your main page and site map(s) would be optimized towards this. Each landing page would be optimized for the specific phrase, "Previously owned Camaro", "Used 1969 Camaro", "Camaro Used 1969" and other terms you deem worthy based on your keyword research.

Hi - thanks for the quick response.

So what if the keyword research reveals that no one is searching for Camaros, but the site is still making sales (suggesting that although people aren't looking for Camaros specifically, its still a popular used car) - in this hypothetical instance (I sincerely doubt that's the case!) would it be better to optimise the page for "used cars" as well.

Does putting the phrase throughout the site strengthen the website overall or have no effect?

I am sure you will have the term used cars somewhere on the page itself but your title and h1 should be for the landing page itself - the first two words of the title and h1 are the most important - don't repeat words in those or anyother h tag (that actually confused me and I was writing it)
The title could be "Used Camaro 1969"
h1 "69 Camaro Used Car"
h2 "Car Had One Owner"
P>Driven by an old lady blah blah</p
h3 "Red 69 Camaro"
p>Original paint color blah blah</p
h3 "Leather interior"
p>4 cows died so you could be comfortable, blah blah</p
h2 "Financing available"
p>We provide financing blah blah</p
h3 "Bad Credit?"
<p If you make $350 a week blah blah</p

You get the idea...

Then you get links to the page using anchor text (varying) to total the keyphrases your optimizing for.

Your internal anchor text shouldn't be car#1 but "Used Camaro 69" or something to that effect.

See,first of all if 2 of your pages are similar and optimized for the same keywords that will surely effect your ranking.any of your page can go to supplemental result(as main 2 reasons of supplemental results are Duplicate Content and Same Title and Heading tags in different pages).Try to make same different in those pages and optimize those pages for the other synonyms of your targeted keywords.

Thanks again both of you for the help - its truly appreciated, but I should point out that I'm not asking for help within the metatags, or asking about duplicate content - its more a general question about how Google ranks pages.

To clarify - both hypothetical pages have different tags, and neither contain duplicate content - it's just that no one is searching for anything but the vaguest search terms (ones appropriate for a main page, like "used cars" in the previous example)

My question is, although not detrimental to overall rankings (afterall - there's no duplicate content), does using the same vague keywords on various pages reinforce the whole site or just do nothing. I.E: If every page mentions "used cars", will the main website go up in google's rankings for "used cars"?

Thanks again, and sorry for not being clearer the first time!

Didn't mention meta tags as they are useless.

I do not believe you have the resources to rank for "used cars" as a search - it is EXTERMELY competitive. You need to find long tail search terms which are going to be less expensive (time and money) to go after.

To answer the direct question, "How Google ranks pages", none of us know the real answer and can only lead you to what we have learned ourselves trying to figure the algo. The most important thing is links coming to your site - each link has a different level of importance based on where it comes from (type of site and its individual importance). The anchor text in those links is the off-page optimization - vary those incoming anchors towards the keyphrases you are looking to get traffic from. On-page is not as important to Google as the off-page stuff. Write each page for the customer using the keyphrases you found to be important to you - no need to "stuff" words or phrases. Code to text ratios are not important in Google.

Making 1000 pages with one theme all optimizing for 2 words as competitive as those two words are will do nothing but frustrate you even more over time. Your site has a theme, your pages are specific.

Thanks mate - that's more what I was after. I should point out though that I'm not making a used cars page, I was just using it as a hypothetical example for a bigger question.

Also I wasn't suggesting the 2 pages would be of the same theme, but that they would be using the same (or similar) keywords, because people are not searching for specific search terms related to the topic of each individual page (not that the pages aren't popular, just that people don't search for their specific content)

If I am not wrong,then you are asking that if you use "used cars" in every pages is that harm full or not.
If I got our question,then it will not harm u.Just be care full in one thing,don't use "used cars" in the starting of your title in every pages.change the position of "used cars" in different pages.