I haven't read the whole article, but this [http://www.wizards.com/magic/magazine/article.aspx?x=mtgcom/academy/3] seems like it might help. In general, Wizards of the Coast puts out a lot of deck building guides, as well as guides to just being a better player. You can look up decks on different sites, such as Tapped Out [http://tappedout.net/], but it can be rather dejecting to see what others have built and know you can't even touch it with a limited card pool.
I only play the game casually. My brother is the really serious one. Still, a few tips that I use are:
1. Avoid mono-colored decks at the start unless you have some really good cards for one (I will say that, as someone who has a boatload of black and red cards, I still cannot make a decent deck of one color). Go for two-colored, and also don't be afraid of three-colored decks, though, you sort of need special lands in order to make a three colored deck really good.
2. Locate a few cards in your deck that are just awesome. See what color they are, and start looking some other good cards of that color. In particular, look for cards that will really help complement your power cards well, and also look for ways to get your power cards easier. While it might seem disadvantageous to keep drawing cards, there are times when you want to draw a card.
3. Try to establish a theme. What is the purpose of the deck. For instance, I have a black/white deck designed around using the Extort ability to dwindle my opponent's life and keep myself alive. I use a lot of tokens to protect myself. Ideally, I want to get one of my Planeswalkers or Teysa out. If that happens, my chances of winning skyrocket. That's just one example of a deck with a definite mission (and a back-up plan).
4. Keep experimenting and be honest with yourself. Could you have done better with other cards you have? Is your strategy just flawed? It takes a while to perfect the deck.
5. Know what your mana curve is as well as your Land-to-Spell ratio. However, don't get too upset when you get mana screwed or mana flooded. It happens to all of us. As a general rule of thumb, 24 Lands is standard in a 60 card deck, but this will change depending on your style of play. My brother runs one deck with only 20 Land cards, and I've successfully played decks that go up to 28.
6. Try to go for a 60 card deck, but don't feel too pressured to stick to the 60 card deck build. The effects of adding 1-3 extra cards is rather negligible if you only plan on playing casually or semi-competitively. If you do plan on really going at this more competitively, then learn to limit yourself to 60 cards.
7. Just because you don't have the cards you want/need to do better, don't keep wasting money. Look for deals on single cards that you want rather than constantly buying booster packs. Also realize that the way they make money is making you feel like your deck is inadequate, and they aren't just going to hand you all the cards you want as that would be counterproductive to their business strategy. Be content, have fun, and don't overdo it.
Edit: Fixed Point 6 to clear up some issues people had. I admit it wasn't well presented originally.