[StainlessSteelCynic]

I freely admit to being a below average GM in the beginning and taking decades to get better.
I've been very lucky in that I've had some really good GMs (and I tried to emulate the things they did well), some really good players, some unimaginative players (that challenged my abilities as a story teller), some players who wanted to push the boundaries (that was a challenge to my abilities to run & manage a game) and very few bad players and I've been a long term member on a number of forums where I could learn from the experiences of other people.
Because I am not a particularly emotional person, I'm not particularly good at conveying emotions in a game (I usually just describe things rather than act them out), so I have a tendency to info-dump on the Players and that can be overwhelming for some of them at times. EDIT: Just look at my two posts in this thread, you'll see what I mean!

Regardless of all that, we're all in the game to have an enjoyable social event, to be in a situation were we can solve some in-game problems and see our PCs survive and thrive and so on. I firmly believe there's no value in running or playing if the game makes you unhappy.

I recall a situation Targan had with a T2k game he was running, it was making him quite unhappy at the time.
I am not sure how I would have handled that situation as a GM at the time but now I have a very good idea of what I would do.
If that means telling the Player that their actions are making other members of the group unhappy and that they need to stop, then I'm much more confident in doing so.
If it's the situation where it means killing off a problem PC to stop the problem, then I am going to do it.

I did have a very clear idea of what I would have done as a Player in that game - I would have done everything I could to kill off the problem PC because in my opinion, they had stepped over the line from being a bad person to being actively evil and they were dragging all the other PCs down with them into evil acts.
I'll allow taboo subjects as a GM (as described above) but as a Player I want to play good guys so I do have strong reactions against evil PCs.

No restrictions, only consequences rears it's ugly head again - I am now confident enough that if a Player screws up the game for other Players or me as GM, then I will give them the choice to fix their attitude or leave the game.

As for curveballs, oh my!
I also learnt the hard way that a group of Players can very often be far more creative than a single person (the GM). Their ability to think of 10 different solutions to a problem that you only thought of as having two solutions is absolutely amazing and terrifying to me as GM.
I've seen Players in D&D games I ran, use Light spells on pebbles, place the pebble in a cylinder and strap the cylinder under a crossbow to make ad hoc flashlights.
I've heard of Players in D&D games buying chickens and grain before going into dungeons because they would throw the grain down a passage and let a chicken loose. The chicken would go after the grain and act as an early warning device.
I've been in a ShadowRun game where the GM planned a specific situation for us to encounter but we decided to stop at fast food joint first because one of the PCs was hungry. The staff seemed unhappy to see us. We wanted to know why.
We had accidentally stumbled on a bunch of crims who were using the store as a front to find people with cyberwear, murder them and then sell the stolen cyberwear on the black market. This was something we were supposed to discover after the specific situation but we unknowingly triggered it early just because one of the PCs decided he wanted to stop and get some BBQ ribs. If he'd wanted anything else, we would have gone to another store and we would have missed the crims (and not messed up the order the GM had planned out!)

I used to spend hours trying to think of every possible solution to any problems I put into the game. After a decade of doing that I finally got comfortable enough to stop overthinking it and start running with what the Players gave me - They didn't go down the path I expected so they missed the encounter I had planned? No problem, the encounter now takes place on whatever path they decided to follow.
So the lesson for me there was yes create encounters but do not hard-lock them in a specific location (unless it's needed for the story).
Players will very often think of something that I didn't!