Just need time to focus and I finally able to get the very basic understanding of how to make GIF animation in After Effects :D
I plan to animate some of the logos that I designed for client as part of my portfolio and to practice with some effects.

You need to be sure that each of your layers are not grouped or create individual units for specific shape that you would want to animate, before importing it to After Effects. For instance, if you want to animate a human character, you will have shape layers of body parts :D

Here's a tutorial of how to create animation using AI file that has multiple layers.  This tutorial is consist of 2 Parts. Enjoy!

 Part 1