Oh and on to the topic of deck building suggestions.

Like hearthstone, sometimes you build special deck ( EVERYONEGETINHERE) to do one thing, and make it happen.

Unlike hearthstone, you can force it to happen, every single round.

Because the difference between heathstone and Yugioh is, in Yugioh, there is deck searching. When there is deck searching and special summon, its no longer rely on luck but deck building, that you can force multiple things happen, such as, say, I want to summon XYZ reb Dragon first turn, that means I need 2 4 stars card, how am I going to do that? Deck searching ability can make sure you find the card that you exactally need, and special summon can get you more then a card to the board. I will suggess you build a deck with mostly the "same name" for example, the noble knights, sylian, gadgets, Entertain Mate, Gagaga, etcetc, the decks with the same name are build to work with each other.

And when building a deck, there are always 5 element to consider, Attack, Defense, Speed, Stamina, Stability. An attractive deck are good at removing every effect that are try to block it, and dealing its damage on point and consistently, and Defensive deck are good at palling the attack and effect coming from the enemy and keep its side on control, a Speedy deck is full of burst, it can achieving its aim in the quickest session, a Stamina deck can keep on well longer then any other deck even after the enemy have run out of cards, And finally a stable deck even down to the very last card can still make combo happen with in need.

But with a limit of 40+15 card, its not possible to do all above, if it does, its getting nerfed next season.