Just finished the campaign (loved it) advice going forward (first Borderlands game)

So yeah just finished up the main missions unto the point of unlocking UVHM1. Im level 35

What's the most efficient way to get to 50?

Also I want to clear out all the side quests would it be better to do these on UVHM1 or should I drop down to easy mode just to get them done as quickly and smoothly as I can

Any other advice very welcome thanks