Alright, here's a quick run down: When in a paragraph that handles dialogue, you have 3 structures. These structures are the quoted speech, the dialogue tags, and the action tags.

So, you seem to already understand how the tags work for the most part, but I'll give the quick rundown on definitions anyways.
Dialogue tags refer to the dependent clauses that express who is currently speaking. Ex: "Well, that's a very silly sentence," Kristoff told me.
Action tags are the independent clauses that express the action the subject of the paragraph performed. Ex: He smiled sinisterly as he stared down his impending doom. "Killing me won't fix your grammar."
It should be noted that while the tags are separate, action tags and dialogue tags aren't mutually exclusive in a given sentence. Ex: He laughed, finding the time in-between syllables to choke out, "This is the dumbest idea I've ever sincerely considered doing!"


Now, action tags, for the most part are gramatically simple, so we'll start there. They are almost always independent sentences, with only two exceptions. The first is the aforementioned merging of a dialogue tag and an action tag. The second exception is when you want to have the action interrupt the quoted speech. Here's a formal example of the latter.
"I'm sorry—" The woman violently coughed, before clearing her throat. She continued after a small pause, "I've got a bit of a cold."

Dialogue tags are unfortunately a lot more complicated, and it starts with positioning.  There are three positions you can place a dialogue tag naturally. At the start of quoted speech, at the end of quoted speech, or in between the quoted speech.
The most typical place you'll find a dialogue tag is after quoted speech. In this position, the quoted speech (almost) always ends with a comma in place of the normal punctuation. Already, there's actually FOUR exceptions to this punctuation rule, but first, a demonstration.
"Hello world," the program output to the screen.
Now, to the aforementioned exceptions. In the case of exclaimation points and question marks, you can actually leave them as is. This isn't formal English by any measure, but it might as well be, because it's everywhere when you're not writing as dryly as me. It helps to preserve the tone of the quoted speech itself. Compare the following:
"They're struggling so much with math," she shouted at you.
"They're struggling so much with math!" she shouted at you.
"How are you going to fix the potholes," the reporter asked.
"How are you going to fix the potholes?" the reporter asked.
You might've noticed that this only covers two of the four exceptions above. That's because the next two exceptions are extra special. The third exception is the ellipsis as an ending punctuation. The ellipsis here is unique, because even in formal English, it should be maintained.
"Why are there so many..." he trailed off, never to finish that sentence.
The final real exception is when you mash a dialogue and action tag together. Because the action tag is an independent clause, this means that technically, this hybrid tag is a complete sentence. This means you can keep the originally intended punctuation AND capitalize the hybrid tag. It's not common to do this, but it is entirely legal.
"This is a very stupid task." He thought to himself, as he whittled away at his keyboard.
Putting the dialogue tag at the front has no unique punctuation exceptions to deal with, thankfully. All you have to do is end your dialogue tag with a comma, and start the quoted speech with a capitalized letter.
Gordon stated, "I don't see this used often in story telling, but it should be noted that it exists regardless."
The final position you can put a dialogue tag is in-between two quoted speech structures. This is the most flexible of the options, because it lets you interrupt a sentence to convey who is speaking at the same time, while also allowing you room to have them start an action that could be implied to be done the entire time they're talking. Because you're interrupting an on-going sentence, you also don't have to capitalize the continuation of that sentence.
"But," the alien enthusastically started, "there are limitations to the rules of lawfare!"

Here, let me novelize one of my favorite scenes, and see if you can break it down into the various structures:
"Let her go!" McNeil ordered, gun raised and aimed directly at the head of the megalomaniac before him.
"Still giving orders, commander?" Kane asked incredulously. "You really should learn to pay attention. I have your mutant and I have your world."
Umagon pleaded to McNeil, "Kill him! Forget about me! Don't let him win!"
Before the plea could set in, an explosion shakes the launch facility, threatening to throw the trio off balance. McNeil kept his gun trained on Kane, telling him that "Your missile's grounded, it's over."
"You're only delaying the inevitable. I have the Tacitius," Kane spoke with a hint of glee, continuing with "I am invincible." 
He looked over at the Tacitius as it rose from the ground and into the center of the room, glowing an ominious orange. His smile widened as he witnessed this. "The Tacitius told me of Tiberium missiles, of invulnerable flying ships, of real time genetic mutation. More than alien, more than human; The next step in our evolution as a species!"
McNeil reeled from what Kane was raving about. "You're not god Kane," was what he fearfully mustered in response.
Kane's smile widened for just the briefest of moments as he restrained himself from laughing. "No, I'm not god." His smile faded away as he prepared to pull the trigger. "But I'm a close second."
A second explosion thundered through the entire complex, throwing Kane and McNeil off balance. Umagon took the moment to escape from Kane's grasp, and McNeil recovered quickly, charging at the mad man. Umagon heard three suppressed gunshots, looking to find the horrific sight of McNeil on the ground and Kane raising. Kane approached the Tacitius, his arms outstretching. 
He bathed in its glow, soaking the moment in as he proclaimed through gritted teeth, "I am the future. The Tiberium sun has risen!"
Kane looked down, feeling a sharp pain in his chest. He touched just underneath his ribs, discovering that his black clothes were concealing his own bleeding. He slowly turned around to look at McNeil, slowly boiling anger turning to surprise as he watched McNeil charge him, wielding a piece of shrapnel.
McNeil impaled Kane, angrily retorting, "Not in my world!"
Kane looked up, horrified by his defeat. McNeil gritted his teeth, and jammed the improvised spear even deeper into his flesh, before Kane slowly lowered to the ground. "And that's an order," McNeil said as he stripped his gloves and threw them onto Kane.
McNeil approached the Tacitius and removed it. The orange that once bathed the misty chamber faded away, leaving only the green lighting behind.


Sorry for the delay, I had to look up a fuckload of terms. I just kind of know this stuff, but that didn't mean I could actually explain it properly.