In Super Mario Bros. 3, every time you score 80,000 points, you get to play the card matching game

Ignoring the grammar error, you are presented with a grid of 18 cards and have to try to match pairs of cards to get the powerups they contain.

If you fail twice, you have to stop and try again when you get another 80,000 points. But! The layouts aren't random. There are eight possible ways that they could be laid out.
And maybe you have a better memory than I do, but I can't remember eight layouts of 18 cards each. Sure, you could write them down, but then you'd have to make sure that you had your notes handy every time you played, which might be OK.
But, take a closer look at the second picture. Notice how the last 3 cards in the bottom row are Mushroom, Fire Flower, Starman? It turns out that those three cards are the same cards in the same order on all eight of the variations! Making it really easy to remember at least the three of them.
In the 'grassy' stages of Super Mario Bros. 3 (like stage 1-2, for example) you might notice that there's a dark green patch at the bottom of the screen.

You may be thinking that was an artistic choice, but if you're properly prepared, you'll find that it's more than that.
Enter one of those stages with a P-Wing equipped and fly down the closest pit (being careful to not actually fall in, of course) and you'll find that the dark green stuff is actually a tunnel that runs most of the length of the stage!

Of course, stuff like enemy fireballs that go through the ground can still hit you if you're not careful, if you stop mashing the A button you'll fall off the bottom of the screen and lose a life, and you can't actually finish the stage from down there, you have to be above ground to hit the Card at the end.
But it's a fun novelty to do once or twice.
In Super Mario Bros. 3, you come across tons of shelled enemies, which you can pick up and carry around. Throw them at question blocks, and they reveal their contents for you.
But, if you take your favorite shell up to a block, and get real close to it (without touching it)

And then let go of your shell, it'll hit the block, and then bounce back toward you

but it'll sail right through you without causing any damage!

And you might be saying "So what? I could just throw the shell at the block from further away and achieve basically the same thing." And you'd be right, you could do that. But this way, you don't have to dodge anything when it ricochets off your target.
A while back I told you about a trick to racking up a lot of lives in Super Mario Bros. 3. But, you kind of have to wait until you're almost halfway through the game to do it. Isn't there a way to stock up on lives beforehand?
You betcha!
Make your way to 1-2, the second stage in the game. Make sure you have the Raccoon Tail and make your way to the pipe that generates an endless supply of Goombas.

Let a few build up around you and then start jumping on them.
It's kind of tricky, but what you want to do is to hold down the A button when you land on them to bounce toward the top of the screen, then rapidly press the A Button to slow your descent. Repeat this over and over (without touching the ground) to eventually be rewarded with

1UP!
Yeah, it's a little bit more work and a little bit slower, but you can do it so much earlier in the game that it's worth giving yourself a little bit of a buffer until you can make it to World 3.
Oh, and this also works any time you can get 3 Dry Bones together in a place with high ceilings.
In Super Mario Bros 3, getting maxed out on 1UPs on that one stage is pretty great, but what about the rest of the game?
Well, every time you finish a stage, you get a Card, which sits down at the bottom-right of the screen.

Collect three cards and you get a 1UP. Collect three matching cards, though, and you get more. Three mushrooms nets 2UP, Fire Flowers nets 3UP, and Starmen get you the pretty awesome 5UP.
So, if you know how to manipulate the cards, you can slowly build up a pretty good stockpile of extra lives.
You start by running into the dark area at the end of the stage at full speed (or pretty close to). Then jump up and hit the goal at 45 degree angle.

Done right you'll get a Star. Every time! Which will lead to

5 extra lives, every three stages or so.
Not a bad ROI, I'd say.
If you're inexperienced at it, Super Mario Bros. 3 is a tough game, made worse by the fact that after you lose your meager 5 lives all the progress you made in each World is negated, and you have to do it over again.
So, like a lot of games, it's very helpful to throw more lives at the problem.
My favorite spot to do that is in World 3-9.
First, stomp on the Koopa Paratroopa and grab its shell.

Then run over to the right, being very careful not to hit the Goomba or the Bob-Omb that's hiding over there. Make your way to the Bullet Bill cannon and kick the shell over to the other side of it.

Then quickly make your way to the platform above.
And wait.
Bullet Bills will continuously be fired from both of the cannons, and the ricocheting shell will take out each one.

Until eventually

1UPs! And you can stand there in safety until the time runs out, which will cost you one life, but you've got plenty to burn at this point.

And, if you're playing a two-player game, it's good form to allow the second player the chance to do this trick also, so that you both have a ton of lives to play around with.
The Warp Zone in Super Mario Bros. 3 is a little different from the one in the first game, it's its own separate World, World 9.

What determines which row of pipes you have access to is what World you were in when you used your Whistle. Anything that's 7 or higher will take you to the bottom row, which leads to World 8. And since we're in World 9, we can use the whistle while in the Warp Zone to...

Go straight to the shortcut to World 8!

Which means that you can do this from pretty much anywhere you want, so long as you've collected at least two of the three Warp Whistles.
Just be aware that World 8 is pretty tough, and if you haven't spent time in the earlier Worlds preparing (i.e. gathering supplies) you're going to have a pretty hard time of it.
In Super Mario Bros. 3 the power ups that come out of the ? blocks will most of the time go to the right.

But occasionally they'll go off to the left

And if you're not prepared for it, you might lose them. But, why do they occasionally go left in the first place?
Take a look at the ? blocks

Where you hit the block determines which direction the powerup will go. Hit the left side and it goes to the right. Hit the right side and it goes left.

You can use this to force the powerups to go where you want them, instead of possibly off into a pit.
This also applies to any of the 1up mushrooms and starmen.
Play Super Mario Bros. 3 enough and you'll eventually come across ships loaded with coins. They take the place of Hammer Bros. on some of the overworld maps. But where do they come from? What triggers them? Good news for you, it's not random.
Let's take a look at the typical end of stage area.

Looks pretty normal, right? But there are five things to take note of here

Once you have all these criteria met, the next time you go to the map screen one of the Hammer Bros. (if there are any left) will turn into a ship loaded with coins.

Hop on in and go to town. It's totally possible to get all the coins on the ship, and the hidden 1-up at the end.
