What's worked for my GMing is that I play in a game that I like and copy what I think the GM did right in overall style and gameplay.
Beyond that, you can look up stuff like The Angry GM or something similar. Here's a column on how to sort your plot threads, for instance, handy stuff that makes you think a little bit.
Plotting is probably some of the easier things to do and doesn't REALLY need to be elucidated on. (well ok... Easier and harder... But I mean easier in terms of needing to refer to the book and bend things around the book.)
But I'll put it this way.
Your party finds a apple that can grow on low oxygen planets. It might actually be a great way to either terraform planets OR a source of food for low oxygen colonies.
How much is it worth? How famous does it make the party?
Some systems this is incredibly easy to get a good amount (I'd have no trouble in say... Battletech, dungeons and dragons, or Call of Cthulhu... or even Exalted)... Traveler? GOODNESS! I give freeken up!
Battletech easily does it because it has a fame system built right in and the money is easily understandable (AND it even has guides on how to handle money built right in. Earning 10% of your total worth is a good starting point). Dungeons and Dragons has a wealth per level system and fame is purely a story construct MOST of the time. Call of Cthulhu and Exalted have somewhat extrapolated money AND CoC isn't based around money so this is more of a bonus.
Traveler has very specific very sporatic all over the place money (fame is relatively fine). You are required to know the system intimately to attempt to penetrate this.
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Dusk City Dwellers (A REALLY interesting game I wish had character creation)... Has no issue here because money is no object. Sure you steal, but all the characters are typically independently wealthy and are doing it for both the entertainment value and for station within their families. They have no real want for expensive jewelry and gold.