is this your first visit to universal?
i only ask because i can remember when i was a universal virgin and had a frantic time trying to get everything in.
if this is your first time, i suggest you be at the ticket turnstyle at 8:30 and hit the parks when they open.
check out the guidebook to see what shows you definitely do not want to miss. for me, the gory make up show i always include at least twice in my visits.
also check to see the times some of the attractions will start. when i was last there, T2 did not start until 10:00.
for us side:
depending on what appeals to you the most, either start at the first street to the right after you enter........T2, lucy tribute, gory show.....down to et, animal planet, back to future, MIB...........circle over to the other side for jaws, and work your way up.
or, after you enter go to the 2nd street to the right and start with shrek, jimmy neutron, twister, mummy, etc side and then circle back to MIB
you could get it in if you start at opening and stay to closing but it will be tight if you take in shows, beetlejuice, blues brothers, etc.
if you are staying on site and do the fotl, you will get almost all of it done.
as long as you don't take time out to eat and shop, it can be accomplished but will be very tight schedule.
some rides are not that long but attractions can be 20 minutes of your time.
for ioa, i did this in one day, a very full day, and hit the high lights.
the water rides slowed me down.
if you park hop, you can get the highlights of both and then repeat your faves on the 3rd day.
it is possible to do both parks in 2 days but you will miss out on many things
i always suggest make it a 3 day event