Best way to export a VM as an OVF/OVA ?

Hi All,

Everytime I manually export a VM using vsphere client, I am getting the resultant ovf of much larger size. ( i.e. size of .vmdk's are much larger, increases by 10% everytime )
I looked at various temporary files and log files and deleted them before taking the ovf, but it also doesnt reduces the size significantly.
My vm doesnt do any huge IO on the disks.

Is there a best practice for exporting an ovf .? ( Ex. SLES based vms. )

Thanks

Nikunj