You'll have to find that "direction" yourself...it's your decision if you want a burn deck (basically slinging spells that do nothing but damage the whole time), a control deck (cancelling the opponent's spells and everything) or whatever. Just find out what type of play suits you. Personally, I'm more of a control guy.
This step usually determines what colours you play. For example, burn would most likely be red, control blue. Of course, you can combine these colours with others, for example, a red/green burn deck.
I recommend buying a pre-constructed 60-cards deck from Wizards of the Coast and try it out. Play with it until you know its "theme", its mechanics. Then try to improve it.
General deckbuilding advice:
A few years ago, it was said that a 60-cards deck should have about 20 land cards, 20 reatuers and 20 other spells. Nowadays you usually have a bit more mana/lands, as in 24 or something. But it usually depends on your cards, especially on the Mana Curve (basically just a diagram that says how many spells you got with converted mana cost of 1, how many of 2, and so on). The average converted mana cost (example: 1 colourless mana and 2 islands equal a converted mana cost of 3) should be around 2 to 3, not higher than 4.
Besides, your deck should always have a theme, that's why it's good to start with pre-built theme decks. Randomly smashing good cards together doesn't do anything, you need consistency, all your cards need to follow a certain goal. I, for example, am in the process of improving a black/blue deck that focuses on dealing -1/-1 counters.
But really, don't worry about all that stuff. Buy a theme deck that sounds fun (meaning the description of the deck mechanics sounds fun), play with it a lot and try improving it. Then play again a few times and see if it works or not. I've been playing for approximately 8-10 years and that's how I started deckbuilding.