User blog comment:BlackMist4848/Guide to Deckbuilding 101!/@comment-25600444-20141230225854

First off, it should be said that there's gonna be a lot of variance on what goes in the build you want for a deck, dependant on a lot of factors such as what world it is (Ancient likes more Size 3s then usual), what attribute / archtype you run within that world (For Katana, Ninjas like to predict and counter opponents moves, while Skull Warriors focus on grave manipulation)  and what you want to do in the deck.

The typical standard build is that the deck Size should be as close to 50 as possible with around half the deck composed of Monsters and the other half, Spells, Items, Impacts.

For Sizes, I usually go for this pattern, again this is up to prefernce and other factors:

Size 0s and 1s = 12 -16 / Size 2s = 8 - 12 / Size 3s = 0 - 4

If you decide to run them, Items should compose around 8 - 10 cards within the deck.

It's best to run only copies of a single Impact in most decks.

Finally, I recommend BlaZofgold blog posts about the science and math behind Buddyfight. Blaise goes into a lot of indepth stuff about the game and what you need to take into account such as sweet numbers (stats your monsters should have to be as effective as possible) and loophole abuses on effects etc.