I have run a Sisters of Battle Mechanized list for quite some time now. I have composed quite a bit of tactica on the subject on what has worked for me.
(Since it's a LOT of info, I'm just going to provide links to the posts on Warseer).

1 - Unit Usefulness Breakdown (6 posts long)
2 - Faith Usage
3 - Mechanized Deployment/Movement
4 - Delivery & Sustainability

Enjoy.