Portal 7.0 upgrading to Portal 7.4

Hi Experts,

We are planning to upgrade portal 7.0 sp20 to portal 7.4.

Please advice if any precautions required and which issues may come after upgrade.

We are also upgrading ECC 6.0 EHP3 to EHP7.

Your response will be appriciated.

Regards,

Vamshi.