Oracle upgrade from 11.2.0.2 to 11.2.0.4

Hi Experts,

As client requirements we are planing to upgrade our oracle from 11.2.0.2 to 11.2.0.4 .

Please tell me is there any prerequisite notes which we need to apply before upgrading Oracle.

System Info-

Window server 2008

ECC 6 EHP 6 (NW 7.31)

oracle 11.2.0.2

Thanks

Chander