Hi KISHORE,
There are no best practices for EAR/WAR max size, depends on your aplication. I'm not aware about any limit.
In my opinion and experience try keeping the size smaller as you can. To get this configuration put out of the ear/war all utility files or frameworks and link them as shared libraries.
With small files the distribution of your application around your cell is faster and you will avoid OOM (Out Of Memory) exceptions deploying.
Hope this helps.
Regards