Instructions
Come up with a deck theme. Beatdown, Single Card Strategy, Weenie and Mill decks are some of the most popular, but with enough knowledge of the game, you can envision and construct a new deck type or an original combo deck.
Keep the 60 card minimum in mind and remember that a deck can only have four duplicates of any one card. You must also keep in mind the format of the game in which you plan to use the deck, making sure not to include any banned or restricted cards. In high-level tournaments, having an illegal deck can result in penalties.
Maintain balance. Work to achieve the right ratio of creatures, spells, lands and mana. If you overstock the deck with cards that require a lot of mana, you risk giving your opponents a valuable edge. The goal is to have good cards and be able to play them when you need to.
Know your competition. Before entering a Magic: The Gathering tournament, understand which deck types are the most popular so you can build a worthy match.
Protect your weaknesses with a variety of card colors. If you have a lot of green creature cards, include sufficient white cards for healing. You must also have some blue and black cards to maintain control and red cards to inflict damage in a pinch.
Make a deck list. This is especially important, and sometimes required, for tournament play. Take note of successes and failures, making future deck adjustments accordingly.