After forty hours of epic battles and embarrassing failures, I realized that Mount & Blade 2 is an awesome game that simply doesn't teach you how to have fun with it. So with this guide I'd like to help you skip past the learning curve and get to the good stuff.
1) What Do I Do?
Your first order of business after finishing the tutorial should be to gain reputation. Once you have enough you'll be able to pledge yourself as a mercenary to one of the kingdoms, and that's where the real game begins. At that point you can tag along with their armies, fight massive siege battles, and eventually even become one of the nobles.
So how do you do that? Fight bandits, do tournaments in big cities, and solve any quests that don't sound like a pain in the ass. It really is that simple.
Video version of this guide (~10 minutes)
2) Hoard Horses
While it's going to be tempting to sell horses in the early game to make quick cash, resist that temptation. Having enough horses for everyone to ride on will greatly speed up your army and make the whole 'catch a bandit' mini-game a lot easier. You'll especially want to collect 'war mounts' as those are used to upgrade infantry into heavy cavalry, which are some of the strongest units in the game.
The only horses you should sell are those ultra expensive noble ones. Once you've selected the best one for yourself, the rest are just pointless.
3) Loadsamoney
So if you aren't selling horses, how do you pay the bills? In the early game it's all about selling the loot you find through combat, doing easy quests, and betting on yourself in tournaments. This won't make you rich, but it'll be enough to earn you some powerful equipment and set yourself up for a cozy midgame.
Once you have a bit of cash to work with, you can also use my favorite trading technique - extortion. Purchase basic supplies like meat and beer in cities where they're basically free, and then sell them to recently besieged cities at absurdly inflated prices.
And once you become a vassal, you'll be able to go fully hands-off and just coast along on passive income from your cities, castles and caravans.

Once you're in the midgame, you're basically printing money
4) What to Do With Prisoners?
As you keep winning battles, you'll find yourself getting overloaded with prisoners. So what do you do with them? Well, after a bit of time you can recruit them into your army which is a great way to replenish troops on the fly. Or you can sell them in city taverns for a bit of pocket change.
When you become a vassal, though, I would recommend donating them to dungeons instead. This will give you influence which you can then use to pass laws or vote on proposals that benefit you - like getting a brand new city!
5) Don't Neglect Your Gear
While you're doing all of this Mount & Blade 2 will bombard you with a truly insane amount of gear. As tempting as it is, don't ignore it, because good gear is the difference between you dying to a random peasant and you being able to shrug off arrows like the terminator.
Early on you'll want to peruse what the bandits have and take all of their best pieces for yourself. Once that stops being relevant, check every city you visit for any special weapons or armor they might have - usually by sorting the shop by price as they'll be at the very top.
And while it might sound insane to give up most of your money for a brand new piece of equipment, that's exactly what you've been hoarding it for. So don't be Scrooge McDuck and treat yourself to a nice new horse or weapon. You deserve it!

The items can be stupidly expensive, but they're well worth it
6) Fighting In Melee
Mount & Blade 2's combat is kind of like rock-paper-scissors. If your opponent is blocking high, you hit them low. If they're blocking left, you smack them right. And if they're turtling behind a heavy shield, you kick them to open their guard.
Not every weapon is equally useful in every situation though, so always carry a 'plan B'. For example, the glaive I used made me a whirlwind of death... as long as the opponent wasn't up close and personal with a big shield. At that point my weapon's massive size simply meant I couldn't actually swing at them.
So to solve this problem, I always carried a short sword - something nice and fast to get me out of trouble and back to carving through people's spleens.
7) Fighting on Horseback
The key to fighting on horseback is to stay moving. The moment you slow down is the moment the thirty peasants you've been terrorizing will rise up and turn you into a pincushion.
But if you're slamming into them at top speed, not only will they not have enough time to react to your shenanigans, but you'll also do bonus damage as getting trampled by a giant war horse tends to hurt.
And when you're fighting alongside other horsemen, try to clear out the enemy cavalry first so you can then rampage across the enemy backline without any interruptions. Do this well and you'll be able to pretty much singlehandedly swing the battle in your favor.

Moments before disaster
8) Siege Warfare
If you like being alive, don't be the first one through the door in sieges. Let your men create a breach, and then join the fight.
Once there, I found that circling the enemy formation and attacking them from behind is insanely effective. The AI doesn't seem to react to you backstabbing them until it's too late, so you can rake in an insane amount of kills, and experience, per fight.
And if you're leading the siege yourself, I'd completely ignore the siege equipment. They're slow, leave your troops vulnerable, and don't really do anything special. I found that just rushing the walls and using ladders is far stronger. You'll be inside the city chopping up their archers before they've even reloaded their catapults.

If you're fast, you might not even see defenders before you're in the city
9) Keep Your Armies Safe
In the mid-game you'll be able to create AI-controlled warbands which go around and earn you money and influence. They're great to have... except for one problem. If there is a war going on, the other AI factions will rope them into their armies and then send them off to their doom. Not ideal.
Since you can't take them out of allied armies, your best bet is to form an army yourself and only invite your own parties. And when the army cohesion starts to drop, just break up the army and then immediately reassemble it without any penalty.
This might sound excessive, but trust me, you really don't want to see how much the AI loves throwing your armies off a cliff.
10) Managing Garrisons
Keeping big garrisons in your cities and castles is a great way to go bankrupt. So what I would recommend is keeping the front line well defended, and dialing back the funding for backline garrisons to around 1/4 of the max. This trick alone will save you a truly staggering amount of gold per day.
But does this also mean you're occasionally going to lose cities? Yeah, but you're probably going to lose them anyway as the AI tends to attack only with massive armies that would crush even your biggest garrisons.
If you want to actually defend them, don't rely on the garrison as they're mostly just a speed bump. Instead, bring your own army and attack the enemy after they exhaust themselves. If you win decisively enough you can then use that as a springboard to capture even more of their stuff.

If you're not careful, castles will drain all of your money
11) Caravans & Companions
Caravans are a great source of money while you're at peace, or early on while you're neutral. So make sure to form one as soon as you can to get that passive income before things get too heated.
In order to do that, you'll need to assign a companion to it, and you can recruit those by visiting taverns. But companions are not only great for leading caravans, they can also lead extra parties once you're in the mid-game, or even run your cities. The higher your clan rank, the more companions you'll be able to have.
And since I struggled to figure this out myself - here's how you can disband a caravan. Go to the Clan tab, select Parties, choose the caravan you want, and then click the tiny little "change party leader" button near the top of the screen. Once you're there you can disband the caravan and your companion will become available after a short while.
12) Is War Sails Worth It?
You might be wondering if the War Sails expansion is worth it? The answer is sadly 'not really', at least not yet. Sailing on a longship during a storm at night is one of those moments I won't forget for a very long time. And the actual fights? Well, setting tiny ships on fire and then ramming them is always going to put a smile on my face.
So what's the problem? Well... you don't really do any of that in a normal campaign. Unless you're actively seeking out ship battles, you can go dozens and dozens of hours without seeing a single one. And for a paid DLC that's all about ship battles, I'd say that's a pretty big dealbreaker.
This is something that can be patched, however, so before you make up your mind give the Steam reviews a quick glance. With a bit of luck, maybe it'll be fixed by the time you're watching.

The atmosphere is so good it really makes you wish there were more ship battles
13) How to Get Cool Ships?
While most of the DLC is self-explanatory, there is one area that I was constantly confused about - how do I get better, cooler ships? As it turns out, each city has a shipyard level that governs what kinds of ships and equipment it'll sell.
So if you want the really good stuff, make sure to go to Tier 3 shipyards as those will have the heavy ships that can be outfitted with fun toys like a flaming balista or a giant ram. And speaking from personal experience, I can highly recommend both!

Got Any Questions?
And there you go. If you have any questions, about the guide or Mount & Blade 2 in general, drop them in the video's comments and I'll do my best to help you out. Have fun!