@andleeb Akhter
First of all, I would take this opportunity to congratulate you on successfully achieving the first milestone of becoming a CSS Officer! Secondly, I would like to wish you all the best for the rest of stages!
You may refer to the following post for detail about psychological test:
http://www.cssforum.com.pk/494328-post5.html
For interview preparation, tips shared by Muhammad Ali Asghar are very helpful. Here is the link:
http://www.cssforum.com.pk/beginners...sghar-dmg.html
If you have any specific query regarding psychological or interview, you may state here. I ll try my best to answer.