The Ins and Outs of Building a Standard Game Deck
1. Rules of a Standard Game
There are a few rules as far as standard deck building goes. The deck must contain at least 60 cards. It's considered illegal to have less than that. It is however legal to have more, although the more cards that are in a deck, the less exposure they all have. Also, a deck may not contain more than four cards of the same name (known as a play set) except for the basic land types Forest, Mountain, Island, Plains, and Swamp. One can have any mount of basic lands in a standard deck. Finally, the object of the game is to get your oppenent(s) to 0 life.
2. Mana (Land) Ratio
This is essentially a matter of opinion. A deck consisting of one third land is recommended however. So for a 60 card deck, 20 of those cards ideally should be lands. If there's too many lands in a deck, then the player risks not being able to play the deck's other cards in a timely manner since more lands will reduce exposure for the other cards. If there's too little lands however, the player risks not being able to play the deck's other cards because of the casting cost of those other cards. Both of these situations can lead to the player losing the game, just in different ways. Be very careful when choosing the amount of land in the deck that's being built, and try to stick to the one third rule as mentioned above.
3. Choosing Colors
Here's a brief synopsis of each color, and what advantages and disadvantages they have.
Advantages: big powerful creatures, trample common, artifact and enchantment
destruction, spells make creatures bigger
Disadvantages: many creatures are expensive to play, fairly weak against flying
Advantages: big powerful creatures, flying somewhat common, first strike common,
damage (aka burn) spells everywhere
Disadvantages: many creatures are expensive to play, mediocre against flying since the flying red creatures are especially expensive to play
Advantages: mostly midsize creatures, flying common, unblockable common, counter
spells common, shroud common, good for drawing cards
Disadvantages: not many destroy effects, unblockable creatures are usually expensive to play, relatively weak against big creatures
Advantages: fairly small inexpensive creatures, flying common, very defensive
creatures and spells, artifact and enchantment destruction, life gain common
Disadvantages: small creatures have trouble dealing damage to opponents mid to late game
Advantages: quite a mix of big/small creatures, creature destruction and
weakening common, life gain/loss common, graveyard abilities
Disadvantages: inexpensive casting cost creatures usually have a "catch", not many flying creatures
4. Building the Deck
Now that all the color's advantages and disadvantages have been discussed, it's
time to build a deck. But what colors to choose? Here's some advice for choosing colors.
A. Monocolored Deck: With a monocolored deck, the player doesn't need to worry about mana cost specificity. For example if a spell costs 3 green plus 4 colorless to play, and there's only forests in the deck, then that's 7 mana total to play the card. You know that the only land you draw will be forest so this takes specific mana costs out of the equation. What's tricky about a monocolored deck however is that you're at the mercy of one color. The player needs to exploit it's advantages and disadvantages perfectly in order to do well.
B. Two Colored Deck: With a two colored deck, mana specificity plays at the very least some kind of role in choosing cards to put in a deck. With any multi colored deck, the mana symbols for each color should be counted. So assuming a 60 card deck, 20 cards should be devoted to basic land, and the other 40 should be creatures and spells. Of the 20 lands, there should be more lands based on the mana symbol with a higher total count. So if a deck has white and green cards, and there's more green mana symbols than white, then more forests should exist in this deck. A good two colored deck should have as close as 50/50 as possible for each mana symbol. If the player diverges from the 50/50 guideline, then they need to put the neccessary mana in the deck accordingly. For example, let's say that 60% of the mana symbols are green, and 40% of the mana symbols are white. A deck like this should have more green mana producers than white. The deck needs to be test played and tweaked accordingly. You need some general luck also as far as drawing the right cards, but at least your chances can be improved with statistics and careful planning.
Choosing which colors to use is the interesting part. It may be best to choose colors that make up for the other's shortcomings. As noted above for example, green has big expensive creatures, and is pretty weak against flying. White has fairly cheap defensive creatures as well as flying. So a deck with cheap white creatures (and/or some flying creatures won't hurt) would be significant early game, while you can put some expensive powerful green creatures in this deck to get damage through. And don't forget about spells. White as mentioned is defensive where green is offensive in that it makes creatures bigger and the like.
C. Three or More Colored Decks: Make these at your own risk. Although it's great to have all the color's powers, it's commonly difficult to execute especially a 5 color deck. Mana specificity is absolutely everything in a 5 color deck. You'll even want cards to help you cast spells (Dawn's Reflection or Pentad Prizm as seen below work well). Count the mana symbols of all of the non land cards and put land in the deck accordingly as mentioned in 4B. With a three or more color deck, it will take some tweaking and practice to make them work well, but it's definitely possible.
5. Creature and Spell Mix
You ideally should have a good mixture of creatures and spells. As already mentioned, the object of the game is to get your opponent's life down to 0, or to make them lose the game by other means. This section could vary based on the strategy of the player, but here's the basics.
Although this is completely up to the player and their particular strategy, it may be better to have more creatures than spells because typically spells such as sorceries, instants, and enchantments are meant for something specific. Creatures are versatile in that they can prevent damage by blocking, deal damage by attacking, and most creatures have some other kind of ability. They stay in play, until frankly they're dead. Spells are commonly for a one time use. Instants can be used to surprise your opponents since they can be played at any time. Enchantments can enhance the battlefield or even the game in your favor. Sorceries are similar to enchantments, only they leave play once cast instead of staying in play. Enchantments and sorceries can only be played during your main phase. The balance of creatures and spells is key to building a deck. You want your spells to support your creatures, and/or help you to win the game.