Any helpful advice or tips? 1 day park-to-park

[branfam]

My DH, DD and I will be spending 1 day at Universal (staying at Cabana Bay) in early June, before checking to our resort at WDW. This will be our first trip to Universal. DD and I are HUGE HP fans and will focus on those areas. While we know WDW forward and backward, we know nothing about Universal, transportation to the parks, where to go first, where to eat.....We need to be done around 6:00 pm on our park day as we are picking DS up at the airport before heading to WDW. I know we will start in whichever park we can as early as we can but other than that......I'm confused and clueless. Any advice would be welcome!