migrating from Joomla to wordpress

I have a very well established site using joomla for the past 10 years or so with good page ranking and established links. I will be building the new WP site from scratch and so there wont be any database transfer and the like.

I need some advice on how best to do the migrating process. A basic step by step guide would be appreciated bearing in mind that i want to preseve my page rankings etc .
Thank you