Moving app data to external sd card Is it possible to move almost the total app size of an app to external sd? example 90% of its data will move to external and the 10% will stay... 

I've tried moving the Clean Master app, its total size is 71 MB but only 20 MB was able to move in the external... not even 50% of total size has been moved...
Easy approach: Link2SD  

Manual method:
If you are sure that the file attributes does not matter, then there's an acceptable way to do this. Root is required.
1. Copy the app data from /data/data/com.example.foo to somewhere in your SD card. Personally I recommend sdcard/Android/data/com.example.foo. If you are running Android Lollipop or up, there will be a symbolic link named lib, leave it alone.
2. Kill the app process. Remove the original data. Open a terminal emulator (or adb). Run  

su
ln -s /sdcard/Android/data/com.example.foo/files /data/data/com.example.foo/files  

That's all. To revert this job, it's a little complex. You'll have to chmod and chown the proper file modes and attributes manually after copying them back.  

Special notices:
Never copy and link the /data/data/com.example.foo folder directly as the symbolic link lib inside will fail, which will lead to unknown behavior. Link every (or some of them at your choice) subfolders one by one.