Here are a quick few things I learned from running my DF game.
I've GMed for a long, long time, but my previous campaigns were wide-ranging, story-oriented, wilderness sandboxes. Loot came on a big scale when it came, the PCs got around on horses and by teleporting and by gates. I needed travel distances, availability of potions, wide-area encounters, and motivations and goals and knowledge for the NPCs. We didn't have a lot of bash-the-door, kill-the-monster, take-the-loot.
My current game is totally inverted, even if it's equally a combat-mad group of adventurers rampaging around. The different setting and different goals ("We must stop the evil wizard we accidentally unleashed on the world!" in the past vs. "Make a profit any way we can!" now) make for some different logistical issues as the GM.
Mostly, it's the same - "Do your homework." But different homework.
Know the Cost and Weight - loot is central to the game, and players are likely to regard almost anything as loot. So I need to note the cost and weight. "Mail shirt" isn't enough, it needs to be "Mail shirt, $150, 16 lbs.)" because I'm going to end up having to either look it up or let them look it up. Even if cost never matters, weight matters a lot right the hell now, and I need to know. I can either write it down, or make up a number that could be right or wrong and then stick with it. Yeah, just being right is easier, it just requires doing my homework. So I write it down whenever possible. Especially for things that change the price - magic and quality modifiers.
Know the HP and DR of obstacles - My players will break things that are in their way. Again, it's easier to just have it down on paper when they try. Doors I know, but I need to have an idea on non-standard obstacles like thinner walls, wooden barriers, etc. for when it comes up.
Put the monster stats in a statline. I use one like this. This saves a lot of time and means I only need to keep eyes on one sheet at a time, since the room description has the monster stats on it. Really crazy-detailed monsters can get flipped to in my monster stat binder, but mostly I don't want to have to.
WYSIWIG Weaponry - Especially for Fodder, if you're using minis or cardboard heroes, go WYSIWIG. He's got a sword and a shield?
That's what he's got all right. Make as few changes as possible. My players are more forgiving on armor ("they all have leather") because they know mini-makers don't always armor up all the stuff that would be armored. But weapons, I just use what the mini is holding. It's easier for everyone all around, and since I started doing this it's made for faster mini setup and faster combat.
If they ask too late, say no. - If they don't give me time to do my homework, or don't do it themselves, the answer is no. "Can I buy a suit of fine elven mail?" "Did you figure the cost and weight?" "No." "They don't have one." If you ask me a week out, even a day out, I'll figure it out. But don't make me spent a few minutes at the table doing it when we could be getting underway, because I won't. I'm not being pissy, I'm trying to keep the game fun. Figuring out gear cost and weight isn't group fun.
Now I'm not perfect on these - I'm still combing through statting up stuff I noted too poorly in the past ("a suit of light plate" - gee, that's helpful chief, how much does it cost and weigh?) but at least I know what my homework needs to be now.