How to optimize the assets for the android platform?

Hi,

In my game i have one city modelling which has all the lowpoly building and compressed textures. I have 30 Idle characters and the 20 animated characters. In that city i have animated some cars and trucks in unity itself. I have exported as a webplayer it is working fine, in the webplayer it is showing the 40 to 50 fps. But when i export it to the android it is not even coming for 20 fps.

I have changed the shaders and i occlued he models even though i did not achive the frame rate.

I need some guidance for optimize the models.

I refer many post i didn't get any clear guidence.

Thanks.