I have a wordpress blog, and i want to target a new keyword. So basically I'm going to create a new post/page and optimize it using Platinum SEO, and add the keyword to the end of my url. From there i will add external links to boost authority and page rank. However should i direct these external back links to my homepage (e.g. www.domain.com or the actual page im optimizing around this new keyword (www.domain.com/keyword)?
Dude, this is a good way of think, YES, this is how you should do. also don't forget internal linking, it's a powerfull "simple" technic that a lot forget.