Defy Danger + Anything Else

It's definitely a game where little differences in the way you describe an action will lead to little differences in how the action occurs in the game fiction... and therefore which move(s) trigger from it. So every instance is unique.

"I duck and weave through the hail of arrows, running at the archer and stabbing him."
"Okay, roll Defy Danger to avoid the arrows, if you succeed then you've caught him off guard."

"I run straight at the archer and stab him."
"Heedless of the arrows? Okay, one of them hits you for 4 damage, but he totally didn't expect that and he's caught off-guard when you get there."

You definitely want to make each decision in the moment because you can't predict every possible situation and variable, so there's no way you can be like, "this Move works like this, all the time."

It's taking me a while to get used to DWs way of doing things. In most games I play, if a character describes a particularly difficult action, I can apply a modifier to their roll to make it harder. DW doesn't do that! I'm not entirely sure what I should be doing instead.

Well, I occasionally tell the conferences and ask with a "well, it'd be damned hard and you'd take -1 forward on it," but I'm trying to wean myself off of difficulty modifiers and that's my methadone. Well, that is unless there's some danger to defy to attempt it, then it's DD and then whatever unmodified.

The question of action difficulty comes up regularly and the usual answer is, "it's not about how hard it is, it's about the consequences for failure." DW is also a game where it's totally legit to say "sorry, that's just not possible" when it comes to a hail Mary move like "I wanna throw the rock across the room, hitting the tiny switch and stopping the machine."

BUT... it's probably more fun to say "okay, but that will take all your concentration so if you fail then you're defenseless..."

Also, use your GM moves in these situations, too. Think of what would plausibly happen in the situation and say what the adventure demands.