Super dooper, extravagansical noobie question

I don't use wordpress for most of my sites but there are all in one seo packs that I've used before and it makes it simple to do the on-page SEO.

The best option is to stop over-thinking this - it's not a science, despite the fact that people try to make it out to be (typically people with an incentive, i.e. to sell a tool and talk their ass off about keyword density, and why it's soooo important when really, it's BS).

Try and target long-tail variations in your copy i.e. try and insert commonly used modifiers. Modifiers just change the direction of the keyword e.g. "cheap", "buy", "compare" etc. If your target search term is "used trucks for sale", try just incoporating the terms "trucks", "used" and "for sale" into your copy; they don't even necessarily have to be in the "right" order, in fact they DON'T have to be in order at all - scatter them if you like, the relevance boost lost would be negligible, Google is all links when it comes to generic terms.

Then, have a look at the patterns in your niche - a vast bulk of queries made to Google each day are completely unique i.e. they have never been made before. You can tap into these by analysing patterns in your keyword research i.e. are there particular modifiers/terms people use more than others? i.e. in the payday loans industry it may be "24 hours", "quick", "fast", "cash" etc. Insert these pattern terms NATURALLY into your copy to increase the probability you will appear for more long tail variations. Always keep conversion potential, not SEO, in mind when creating copy.

ON TOP OF THAT:

• Insert the main target keyword once or at most twice in the body of the page. Then forget it.
• Insert the target term in the filename (URL) of the page.
• Insert the target term in a header, sure why not - hardly the end of the world if you don't though. I don't bother in most instances, just looks spammy, IMO.
• Factor in ALT text if you like.
• Target keyword in the page title - some will suggest keyword prominence so sure, stick it at the front of the title. Page titles should be unique across the site - try and be consistent for branding purposes i.e. include the brand at the back of each page title or if everyone knows who you are, the front.
• Target keyword in the m. description - the m. description is NOT a ranking factor, that said inserting the target keyword will increase the probability that Google will choose to display it for the selected target keyword (otherwise they may just choose some relevant text on the page which IMO, is better for CTR).
• Meta keywords = irrelevant, other than to allow people like me to steal your KW research (in most instances I probably wouldn't want to).

With the page title, try and keep it to 65 chars. in length (inc. whitespace) otherwise it will be cut off from view in the SERPs; m. description should be kept to 165 chars. With the m. description insert your telephone number for click-to-call purposes and for users browsing on smartphones. Take a look at microformats, HTML chars. in the description and universal search optimisation, too.

Other than that, on-page = basics pretty much done.

Have you looked at on-site?