Well, having played Magic Online for the past month solid and participated in more drafts than any human can possibly justify, I've gotten fairly good at it. So I thought I'd offer ten recommendations to those of who you are new to drafting and want a fighting chance.
1. Nothing wins like warm bodies.
Nothing will win...or lose...the game like the quantity of creatures you draft and put into your deck. Even if you think you've got some sort of neat trick, nothing will cause you to lose faster than not having blockers and attackers, the meat and potatoes of Limited.
2. Learn to recognize bombs.
By 'bombs', I mean cards that will be difficult for your opponent to handle. Dark Banishing, for example, qualifies as a bomb, because it can take out your opponent's biggest and best creature for just three mana. Kirtar's Wrath qualifies as a bomb, because it's a board-clearer that can reset the game in your favor if you play around it. Even cards like Amugaba are bombs, because it's a big fat flier that bounces, making it huge and relatively immortal. Get bombs for your deck; they're in there somewhere!
3. Choose colors early.
Nothing's worse than drafting decent cards in all five colors because you haven't committed to one, then realizing that you're going to end up playing a five-color deck. Commit to a bare minimum of two colors (a mono-color deck is possible, but will almost never be any good), and choose well.
4. Know thy format.
If you're drafting 7th Edition, can the cards really support a blue/red deck? Does white/red look good in Odyssey? Of course not! The best thing to do is to know what you're drafting beforehand and consider your options. Realize that you'll probably have access to most commons, have a decent chance at a few uncomons, and can't count on getting any given rare at all.
5. Realize that "rare" doesn't always mean "good".
While this isn't so true of Invasion block, where some of the best cards were rare, the simple fact is that rare-drafters (people who'll just take any rares they see) may get more rares out of the draft, but they also make it a lot more difficult to actually construct a decent deck, making achieving a ranking worthy of any kind of prize an uphill battle at best.
6. Remember, what doesn't go into your deck goes into someone else's!
I'm drafting Odyssey, and have committed to red/black. I get passed a pack with three cards left in it: Rites of Initiation, Coffin Purge, and Shelter. What do I take? Shelter, of course! Why? Rites of Initiation is of only potential usefulness. Coffin Purge has no actual effect on the board. But Shelter could be responsible for the death of one of your creatures. I don't want to see Shelter on the other side of the board, so I take it. When there's nothing good left for your deck in a pack, take a bomb, or at least a warm body to deprive your opponent of same.
7. Beef: It's what's for dinner.
As tempting as it may be to grab the little, easily castable guys, remember: draft games seldom end quickly. As such, a quick creature rush can often be stopped flat in its tracks once you start playing your bigger guys and making attacking involve losing creatures left and right. This isn't to say that you shouldn't draft any low-cost creatures, especially ones with neat tricks attached to them (Mesmeric Fiend), but remember that especially in draft, slow and steady wins the race.
8. Deck construction is key.
Once you've completed your draft, look at your deck and consider what's going in it; you can't (or rather, shouldn't) use everything, after all. In a 40-card deck, 15 creatures would be considered *barely* adequate, and I recommend more. Instants, interrupts, enchantments, and artifacts are all well and good, but remember that only the best ones should earn a spot in your deck. Ghastly Demise goes in, Peek doesn't. Shelter goes in, Primal Frenzy doesn't. The vast majority of your non-land cards should be creatures to give you a fighting chance.
9. Don't forget your land!
Any novice realizes that you need a decent allotment of land to make your deck work. But how much is enough? In a 40-card deck, 16 land is usually enough to get you where you need to be. But look at your deck once you've created it. How many double-mana symbols do you see? Playing green/red with lots of cards that cost double-green? Consider going with 9 Forests and 7 Mountains. Do your spells have a high casting cost? Consider throwing an extra land in there to bump up your percentages a bit. Be flexible; while I recommend staying as close to 40 cards as possible, go as high as 42 if you need to.
10. Evasion is king!
I can't tell you how many games I've won with the unstoppable combination of...Escape Artist and Frightcrawler. That's right, the ability to hit your opponent is key; you'll never win by staying on the defensive, your opponent will overrun you eventually. So while creatures are good, evasive creatures are better. Even 'uncastable' evasive creatures like Face of Fear are good, simply because it's a 3/4 body that can become very difficult to block.
Hopefully, these ten tips will make you a better drafter. Now, go out there and win some packs!