I have been playing Magic the Gathering for several years now and I have a solid understanding of basic strategy and deck building. Until now I have only played against a single opponent. Magic the Gathering supports games with more than 2 players as well and I want to explore such variations.

The first thing two friends of mine and I will try is playing a free-for-all (3 players) where everybody can attack every other player. This changes the game a lot. It feels like attacking gets almost impossible and your best chance is to wall yourself in and hope for the best. Every fight between two players will usually help the third player the most. At least that's what I expect from a free-for-all.

Before I dive into this experience heads on, I want to know what the typical mistakes are, that a beginner should avoid in MTG games with more than 2 player. I am mostly concerned about deck building and game strategy.