Look, we tend to be a creative lot, we have all our own tastes, influences and styles, this is not going to be an easy task.
I would first suggest that anyone wanting to give out their advice check out Starnage Magic's DM merit pages...HERE!
You will notice to the right of this article my Merit Badges and by clicking the image you can see what each badge means.
That is my first bit of advice...what you didn't catch that? Ok I will explain.
How to be a good Dungeon Master: Lesson One
Look, you got to understand one thing about the OSR and the folks in the OSR, We are a scruffy and varied lot, we have strong opinions and deep core beliefs in what makes a "good game". Because of this it is best to first find a blog or a article or even a *gasp* forum post, written by a Dungeon Master you "like" or share some common interests in.
This may be hard to do, Internet being what it is for all you know I'm a super intelligent dog tip tapping away at a keyboard in some secret military research facility...thing is I'm a self hating dog, I hate dogs....
It's true though, making "friends" or even trusting folks on the internet is a scary prospect. But maybe after a bit or if your just a trusting person, dive in.
Moving in this direction study up on the DM's work, his or hers advice, look into what influences them. Like a Film Director, even though you may not have a lot in common with the person maybe their politics or religion or such, does not mean you don't share interests.
Wait did I just contradict myself, I think I confusing myself a bit, let me try again. Josh Whedon, I don't agree with his political views nor do I agree with his take on religion, but you know what, the dude is an artist, its incredible. This man seems to be able to look past his own beliefs or maybe even be influenced by them and create incredible characters and stories.
That's what makes a good DM a person that draws from what and who they are to build intriguing characters and stories. But how does he do this? Well that's a good question.
Look, you have to read, watch movies, dig deep into what you like, why you like it and then how you can use it. What is that wrong or something? Why? Look when was the last time you saw a romance movie an action movie HELLS NINE BELLS, ANY movie that was not influence some how, some way by...William Shakespeare. Come on really, it's true, or it may be my opinion but when was anything made in Hollywood ever really a "ORIGINAL" work?
Look even artist, rip of other artist off, the key is they all put a personal twist to it, something that makes it "their own".
Looking at my own campaign setting, Ganth, I have stolen, begged borrowed and blatantly ripped off a vast swath of legends and lore both real world and fictional. It's true, and so has Gary Gygax...ouch, yes I said it. But even Tolkien did, Hell's Bells even Gandalf wasn't all Tolkien's...
Look it's ok, and that's what this first bit is about. You need to find some one you can steal from, emulate or just maybe borrow from.
So the first step in becoming a better DM, Find a mentor, and stab him and or her in the back, stealing all his and or her work and claiming it for your own...BWAHAHAHAHAHA!!!!
No maybe not that extreme...but look at their style, their influences and practice and start finding ways to twist them to your own EVIL PURPOSES!!!! BWAHAHAHAHAHAHA!!!!
You always need to be the kind of person that admits where his sources come from, don't be a complete piece of crap, really, I'm serious, all fun and games aside, don't forget where your idea came from, and respect that. Don't be the Guy that claims he was the one that created Drizzt because you knew R.A. Salvatore in High School and he stole it from you one night while ya'll where gaming...jerk.