Should I use a domain separate from the website which I'm trying to push up in SEO terms that links back to my priority website?

For example, I understand that blog marketing can be very effective if done correctly. Should I include the blog within my website http://www.justnewlistings.com or should the blog be on a separate website that always links back with various anchor texts to my main website JustNewListings.com?

Started looking into this before but it got too complicated for my limited time. What is the proper plug in for wordpress to tag one's posts effectively? So ignorant about this...but aware of its potential.

jay

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