First things first.
Log into your blogger dashboard and click "settings". You will see at the top "Import blog - Export blog - Delete blog". Click on "Export". Then click "Download". Download it where you can find it, it will look similar to this "blog-11-10-2011.xml". This is a back up of your blogger posts, comments, and other meta data should things go wrong.
Then in your wordpress admin panel click "tools" then click "import".
Next you will be given options as to what importer you want to use, in your case that would be blogger. Click on the "Blogger" link and install the plugin. After install click "Activate and run".
You have to authorize the plugin to access your blogger account. Just follow the instructions.
Next you want to do "301 redirects". I didn't know there was a plugin for that, you can try a plugin if you like. I prefer the manual method, but as I said it's tedious if you have a lot of posts and pages.
This is what my 301 redirects look like in my wordpress .htaccess (Yours will depend depending on your choice of permalinks)
redirect 301 /2011/10/my-blog-from-blogger.html http://www.example.com/2011/my-blog-from-blogger/
You have to know every one of your old urls and you have to know what your new urls are going to be. And for every url you have to create an individual "301 redirect" for each.
In my situation, I had a custom domain at blogger. I pointed my domain away from blogger and unto my new hosting account, then I did the import. I only had seven posts and 10 pages so it was easy to do only 17 301 redirects.
I hope this helps.