My Renew Macros for Warlock & Pet are as follows:

#1
/follow WarlocksName
/target WarlocksName
/cast Renew

#2
/follow WarlocksName
/target WarlockPET
/cast Renew

(this will ensure that even if you somehow get stunned or tripped - which breaks autofollow, you will follow on the next renew cast)