Speaking of GM advice, I do recommend jim’s book on the subject.
Even if you have decades of experience it’ll give you things to think about.
I need to bug him about making a PoD version available.
https://www.drivethrurpg.com/en/product/535848/a-good-book-for-bad-gms
Yesterday's links:
Review: The Electrum Archive
https://www.valerialoves.com/the-electrum-archive-is-prescription-medication/
Suddenly Ogres
https://docs.google.com/document/d/1MC_W_qxY7kScRK_2arLhGvATX0HyQz6dTIKFj_HI2T4/mobilebasic
GM advice
Favorite RPGs 97 - 90
https://oldmenrunningtheworld.com/my-101-favourite-ttrpgs-97-90/
"Should I look up rules during the game or just wing it?"
Your players have never read the rules so how would they even know?
"How much prep time should a GM put in before each session?"
The same amount your players do. (NONE)
"Is it Ok to fudge die rolls?"
Die rolls are just there to make a pleasant sound while you think of something to do to the Barbarian's family.