I have watched the movies.  I have read the books. I still don't get it.   How the heck did the scrawny little Rebellion bring down the ever-powerful Empire?   I mean look at those Star Destroyers!  And the Empire had like thousands of them, right?  What did the Rebellion have?  A handful - okay, even a couple hundred - Mon Calamari cruisers (which are great in Sushi by the way).  Look at the Imp-Star next to a M.C.C.:

Imperial Star Destroyer: 60 heavy turbo laser cannons and 60 ion cannons.
Mon Calamari Cruiser: 48 TLC's and 20 ion cannons.

Imperial Star Destroyer: 3 full squadrons of TIE Fighters, 2 full squadrons of TIE Interceptors, and one full squadron of TIE bombers... 20 (TWENTY!) AT-ATs and 30 (THIRTY!) AT-STs (which we know trounced - ahem - Echo Station),  and a FULL DIVISION of Storm Troopers.
Mon Calamari Cruiser: A bunch of Googly eyed space squids. Don't get me wrong here - I like Ackbar... but I don't know why.

Looks like the Rebellion only has enough power to call down the thunder, if you know what I mean.  Looking at these figures makes you think - know - all those books are wrong.  After the end of the last Special Edition movie - after the huge statue of the Emperor fell - hundreds of TIE bombers squashed the revelers into sticky goo, and the Empire, while shaken a bit from the loss of its leader, came back with a solid right hook and trounced the Rebellion Rocky-style.  And any one not wearing white armor was pretty much toast. I am sure there would have been plenty of candidates for picking a new Emperor.  Surely the mighty Empire didn't fragment like a sheet of glass!

But then I remembered... I remembered the highly vaulted and widely feared Storm Troopers.  How many times did they have the chance to blow away all the key heroes as they ducked into the Falcon and dusted off?  I mean, in their own Death Star for one!   From like 15 yards at most!  Of course none of our heroes took cover - they were stand up targets!  Who even stood still to fire back!  And the Imps never even grazed them until the end of Return of the Jedi!

Let’s count:

Tatooine, the Death Star, Bespin (while Chewie was even carrying a droid on his back), ahem - Echo Station.   As bad as this is, the Stormies even go to ENDOR and get pummeled by enthusiastic Care Bears!  We didn't see one trooper coldly blast an Ewok, did we?  ONE casualty, from an AT-ST blast,  that was all.  And I bet the guy in the gunner seat got a good smack to the back of the head: "Now look what you done!"  They get their butts waxed every time.  If the Empire had had any REAL troops, the Rebellion would have been toast.

So the question isn’t why the Stormies fell apart in all those defeats, the question is why did they have any successes in the first place?  My theory is, they never won.  Anything.  Let’s look at the their alleged wins and what REALLY happened.

TANTIVE IV.
The Tantive IV is called for some reason a Blockade-Runner. As history teaches us, Blockade-Runners were fast ships used to run past enemy ships blockading ports and harbors.  Let me say that again – they were FAST ships.  One would assume that they would be faster than a STAR DESTROYER, the main vessel used for blockading.   The designation of the ship type of the TANTIVE is a Correllian Corvette.  And the Destroyer is, well a Destroyer.  In Navy terms a Corvette is faster than Destroyer.  So… What happened here?  Well, it’s my happy duty to tell you - here is the real story.  Jonas Marsh – That’s who did it.   Normally Imperial gunners couldn’t hit water if they fell out of a boat.   But Jonas was a former Womp Rat hunter on Tatooine.  This boy could shoot.   He was able to make the critical shots that counted, and to the dismay of every one, the Tantive IV was stopped just about a second before her turbo kicked in.   Interesting thing to know is that Jonas was given an award for his good shooting but 45 seconds later while carrying a dish of frozen yogurt, bumped into Vader and was subsequently choked almost to death.  Vader said afterward "If I wanted Vanilla, I would have worn WHITE."  Jonas was able to survive only because Vader only actually kills deck officers.  Jonas then skipped out and joined the Rebellion and can be seen on guard duty in a crow’s nest on Yavin.  Go, Jonas!

The Sand People took out the Jawa Sand Crawler.
(I don't care what Ben said, he was a liar anyway. "The Certain Point of View" argument doesn't hold water unless you’re the President of the USA.)
Here is what happened - the Stormies saw the Sand Crawler and pulled a Monty Python routine: "RUN AWAY! RUN AWAY!" Then they built a huge wooden R2-D2 and filled it with Tusken Raiders, which turned out to be a good idea and worked for them - even if the idea came from Trooper YL-532, other is know as "The other brother Darrel" who said in a perfect Beavis voice "Uh-Huh... You know what would be funny, Butthead?"  The Sand People, who are naturally cranky and hate being packed up in a wooden droid,  were especially pissed when the droid'o'wood was opened by Jawas, with whom they have a Crips and Bloods feud thing going on. They all got into a fight over ownership rights of the big Artoo. Then the Stormies came by the next day, and upon seeing the smoldering ruins laughed and went off to play Frog Baseball.  (By the way, the Tusken Raider's aren't that bad.  Yeah, they kicked Luke's butt, but that was for spying on them with binocs and a rifle.  They just thought he was a potential rock top sniper and acted in perceived self-defense.   Then, okay, they stripped his speeder.  But hey, this is nothing that doesn't happen in East LA!   The Sand People run at the sight of a pissed-off old man who's yelling and waving his arms around like a certified nutter…. Like I said - just like LA.)

Poor Uncle Owen and Auntie got scorched up by some Bill Collector.
I mean, look – the Imps couldn’t even get one little girl to talk, how do they expect to get any answers from some gritty moister farmer?  Getting ANYTHING from a farm that they don’t want to give or sell you is impossible.  I was in Idaho on a motorcycle that was out of gas and the station attendant didn't like my looks, so he hung the closed sigh in the window.  I was going to pay for the gas I swear.

All in all - the question of "How did the Rebellion win?" is really, "How did the Empire take over?"  I can tell you how (even though Lucas will disagree):
Ackbar was off tooling around with Premier Mothma in his Cruise Ship and was gone for a couple of days.  They came back and the kids had taken off with the Republic’s keys.  And that reminds me - When Ackbar was asked by a friend over the space phone "How did your date to the drive-in go with Mothma?" he smiled and said "Home Run" ‘cause he thought he was alone on the bridge, but Mon Mothma was right behind him and heard, and slapped him in the back of his head... and Ackbar was like "HOME ONE - the name of the ship, Babe - the ship! I swear!" So the name of the ship stuck - as did the nickname "Mon" on her...