Saturday is generally busier than Sunday. Sunday is the slowest day.
At the parks, arrive at 8:30 and do the rides in this order:
IOA:
Spider-Man
Fearfall
Hulk
Cat in the Hat
One Fish, etc.
Get a Universal Express ticket for Posideon's Fury (if available)
Dueling Dragons (Fire and Ice)
JPRA
Ripsaw Falls
Popeye
Posideon's Fury
Caro-seuss-el
Sinbad
Ticeratops Encounter (if open)
Then enjoy the park at your leisure
USF:
Universal Express ticket for Hanna Barbera
MiB (if you want to ride together as a group)
BTTF
Jaws
Earthquake
Kongfrontation
Twister
Hanna Barbera
T2 (if show is available. If not, grab a UE pass)
Then enjoy the shows and other rides you liked at your leisure.