So I went deep into the tank, and this is what I emerged with. You see, there are several very simple things that players do not do. Minor things more often than not, but cumulatively they have a massive effect on your game. I managed to brainstorm ten separate things that I can talk about; today I'll present six of them. Others had to be discarded for future articles because they contained too much meat to be generalized over. Many I have briefly mentioned before, but they are important enough to review again. Here are some tweaks to improve your game:
1) Know every card in the format.
This helps you in a myriad of ways: When drafting you know if you can let a pick slide in favour of something else because there is redundant similarity in other cards. When building your deck you know whether you have to include certain answers main or not, like Disenchant effects. When playing, it is important to know what the worst thing your opponent can do to you, so as not to over commit (cards with split second will often change how you play, for instance). It helps to work out what is in an opponent's hand if you there was a better card he could have or would only make a certain play if he had a specific card in his grip.
These are all very crucial aspects of the game. Several of them help you ascertain further information, which can only benefit you further. The most important aspect of knowing the cards in the format is knowing the tricks. A trick is simply something that can be done at instant speed (or a devastating sorcery such as Boom, Tromp the Domains, or Damnation). By knowing them all, you can ascertain what your opponent might have by how he taps his mana and by how he attacks. You can make the correct blocks and turn bad combat phases around. You can read more about this here.
2) Know your deck.
These are all decisions that you should be making whilst drafting and building your deck, but when you are finished, you can examine the finer things. Some decks are more resilient to mulliganning than others, because they have more early drops or fixers. Know what type of opening hands you can keep because you have good odds to draw into a good state. Know how many cards you have on step of the curve so you work out the odds of an Erratic Mutation or Judge Unworthy at any given time during the game. The options are endless.
3) Know your sideboard.
Many players forget they have a sideboard in Limited. They finish Game 1 and immediately start shuffling up for the next game without a glance or thought about their sideboard. There will almost always be a correct build for the maindeck but due to the many variables that the Magic universe throws our way, you will often need to change cards.
Some sideboarding is obvious because it is similar to what you are used to doing in Constructed: bringing in answers to specific threats, like Disenchants; or bringing in creatures like Slipstream Serpent and Viscid Lemures against the relevant colours; or sideboarding out cards like Death Rattle against a mono-green deck. Some cards in the maindeck will scream to be taken out and some cards will scream to be boarded in. This, however, is only the beginning.
Sometimes there will be specific cards that your opponent has that will force you to make changes. If they have many ping effects and things that make life difficult for the one-toughnessed, then you should board all the weaker ones out. In a Sealed deck, when two colours are incredibly close in strength (this happens far less often than most people think) it might be correct to switch colours to create the correct tempo swing. If your opponent played two Celestial Crusaders and you do not play white main (so he will not board them out), if your white cards in the board of your sealed are equally strong as one of your currently played colours, maybe you should consider the switch.
Pick up your sideboard after every single game and re-evaluate.
4) Write down every card your opponent plays.
Pay special attention to his tricks. I either asterisk them or write them in a separate column. Every card that he will leave mana open for or will wreck you in some way should be specially noted for easy in-game reference. If your opponent makes a strange play, take a moment to review all the cards you've already seen. It will often be the case that the answer lies in your hastily scribbled notes.
5) Do all of your thinking during your turn.
When your opponent says "Go," it's time to think. You may have things to do during his endstep, or during your upkeep. Now it the time to begin thinking. When you're done, progress to your first main phase. And don't you dare drop a land into play yet! Countless games are lost because people automatically put their only land into play. When you draw, shuffle your hand and then review. Here is where you will do all the thinking you will do for the entire turn (including your opponent's).
Think about what you will do this turn: Should you make a land before or after combat? Should you make a land at all? Will you play something pre-combat? What will you attack with? How will he block? What are all the possible tricks he may have and what are all of your responses? Depending on what happens in combat, what will you do in your second main phase? How should you tap your mana to maximise both playing spells in your hand and to bluffing potential cards in the format? Do you have any effects for your opponent's upkeep or draw step? What are all the things he can play and how will you respond? If you have a counterspell, what is the range of cards that are worth you countering otherwise thinking too long when he casts them will give it away? What will his attack be depending on what he is holding and will draw? How will you block given all the cards he can have? And, finally, what will you do in his end step?
This sounds like an awful lot of variables. It is. This is one of the greatest skills in Magic. If you had infinite time, this process would be flawless, but we do not have that luxury so you will have to get into the hang of doing this so as to speed yourself up. You will often take shortcuts, such as allowing yourself reflection time of some of your opponent's plays when he makes them. The better you gelt the easier this will become. See how important the previous skills now become—you need to know the format, your deck, the cards your opponent has already played, etc.
6) Think about which land to play.
During deck construction you memorized your deck, so that you know every card with a double mana cost. Sometimes you will have an awkward deck with both Llanowar Elves and Foul Imp; obviously if you draw both you won't be too happy. It is important to know which land is the correct one to make each turn.
Here is an example from a Constructed game I played recently. My opponent has a Terramorphic Expanse in play. I had an Island in play and my hand contained an Urborg, Tomb of Yawgmoth, a Plains, a Disenchant, a Sudden Death and a Cancel. Which land should I make? My opponent might well be playing a deck also containing Urborg, so I do not wish to be Strip Mined. He might be playing a deck with land destruction and I might draw more land, enabling me to protect my Urborg for when I need it. He might be playing Prismatic Lens, which I might want to Disenchant. I could draw an Island next turn to play my Cancel, but if I make the Plains this turn to keep the Disenchant open, then I will force the choice between Sudden Death and Cancel next turn.
The other crucial mistake that I see players make time and again is simply not making their land. Somehow people think that shuffling three or four land together in the late game with lure their opponent's into thinking that you're holding spells. This ruse seldom works. You should only hold land back if you have a very valid reason for doing so, such as having a Boom in your deck. People often claim that they have a Looter il-Kor or a Careful Consideration that they might draw in defence of them sandbagging lands. If you rip Consideration in the late game then you'll be ecstatic anyway, and you will probably draw into one or two land off it anyway which can then be discarded!
You should only ever hold one land back. This way you will never jeopardise missing a land drop. Almost every Limited deck has something to do with vast amounts of mana, be it a pump guy or a Fathom Seer into two creatures and then leaving enough mana up for your Flickering Spirit. There will be bizarre games that last for forever where you winning will depend on you drawing your fourteenth land so that you can play Bogardan Rager and still create a guy from your Urza's Factory. Your opponent might even draw a Mindstab and deny you the chance to ever make those land!
That's all for now. I will continue these soon. For now, as of this writing, I'm off to play a deck with 50% too many cards with a thousand other Europeans—too bad there are no more Limited tournaments this year until the draft section at Worlds. Ooh, and San Diego, kind of... and Nationals... I guess there's hope yet.