Mechanics alias the strategie of your deck you want to play. It's hard to tell you the musthaves if we don't know what you wanna play. For example:
This Deck works with the "Bestow" and "Heroic" mechanic:
https://deckstats.net/decks/17001/106685-gift-of-the-gods-born-of-the-gBestow means you can play an (Entchantment) Creature or you can play it as an Enchantment on another creature for its Bestow cost. Heroic means, for every spell that target a creature with Heroic, it gets something, like a +1/+1 Counter on it. That means, this Deck is playable as a nearly fast Deck with small creatures or a slow Deck with some big creatures.
This Deck works with "Outlast":
https://deckstats.net/decks/17001/138167-abzan-siege-converted-ktk-casuOutlast means, you can put a +1/+1 Counter on a creature for tapping it and paying the Outlast cost. Depending on which creature you got on the battlefield, every creature with a +1/+1 counter on it gets an ability, like flying, first strike, deatchtouch, trample. So you can get a Flying creature with deatchtouch, firststrike and trample which is already a
bad ass combination. To crown it all,
Ivorytusk Fortress lets every creature with a +1/+1 counter on it, untap during your enemies untap step.
This Deck is all about getting Lifepoints and work with them:
https://deckstats.net/decks/17001/115615-price-of-glory-m15-intro-deck-Get as much Lifepoints as its possible to push your creatures and use abilities of them for paying with lifepoints.
This Deck is a so called "Mill" Deck:
https://deckstats.net/decks/17001/106642-dimir-intrigues-budget-multiplThe strategie is to put the cards of your enemies libary directly into his/her graveyard. If you don't know... if a enemie should draw a card and he can't (for example at the beginning of his upkeep)... he looses the game.
There are a Lot of good mechanics in mtg which want to be discovered by you. Some of them seem to be illogical at the first sight, but can be pretty good in combination with other mechanics. My hint for you... search for some Decks which are described pretty well. Which mechanics they are using and which combinations working pretty fine and find a way to play your own deck.
Also a good hint (that's how I started to play mtg), buy some of the Intro Decks, (for pros they are lame, for beginners they are pretty good) and work with them, try to make them better, search for cards which would fit perfectly into that decks. That's the way I did it.
In this overview you can see my converted Intro Decks (and the others):
https://deckstats.net/decks/17001/?lng=enTake some time, look through them, read the description to understand what they are doing. Otherwise there are many many hints for beginners in forums and blogs.