All in One SEO for WordPress
There are many SEO plugins out there for WordPress blog, and I have covered some of the best here at ShoutMeLoud. All in one SEO is another popular SEO plugin for completely optimize a WordPress blog. For a newbie blogger, configuring All in One SEO plugin could be quite tricky, and without configuring the plugin, AIOSEO plugin is as good as not installed.
Before you start configuring this plugin, I highly recommend you to prefer installing WordPress SEO by Yoast instead. Free version of All in one SEO plugin lacks many important features, where as WordPress SEO by yoast, which is also a free plugin offers many advance features (Social SEO features).
WordPress is said to be optimized for SEO by default but apart from default settings, there are many settings we need to do to make it rock-solid for search engine. Here is a complete configuration guide for All in one SEO WordPress Plugin, which will help you to make your blog search engine friendly.
can i activate WordPress SEO by Yoast and all in one seo two plugin at a time? | Yahoo Answers
You are able to do this, however they may conflict with each other when you are trying to post the SEO tags, title and keywords.
Also you might want to check simply by installing the two. This will give you a first hand look at if there will be conflict.
Which works better for a newbie on SEO Wordpress All in One SEO Pack or Wordpress SEO by Yoast?
I prefer Yoast as I generally find the interface and out of the box functionality to be a little better.