Put the keyword in the title. Have a variation on the keyword (plural, conjugation, alternate spelling, related phrase etc.) in the first paragraph and conclusion. Use a subheader or two (h2 or h3 tags) and use the keyword or a variant in them. Instead of h2 or h3 tags, you can use bold or italics for subheaders. Do NOT bold/italicize keywords throughout a post - it looks like textual acne and is really horrid. You're not improving your SEO that way anyways. If you have a picture that's about your topic, describe it truthfully, and don't stuff keywords into the 'alt' attribute. If they fit in naturally fine, but otherwise, don't bother. Use keywords in URLs; this is good in and of itself for a small boost, but more importantly some people will link using your URL as anchor text. So if your URL has keywords in it, those links using the URL as the anchor text will feature your keywords.