Hello, how are you? I would like to start this off by saying how much I LOVE your advice column, although my biology grade has suffered from my obsession with SparkNotes. I mean, how is Meiosis supposed to be interesting when something like SparkLife exists?! Exactly my point.
Ahem... getting back to the subject I have a crush, and not as in the orange soda. Anyway, I've really liked this guy for a while, and he never starts our conversations, but he's always making eye contact (as in ALWAYS, like from all the way down the hallway, I'll catch his eye), and I don't know if this is just me being crazy, but he usually seems to enjoy our conversations, although sometimes it's a bit awkward, since I'm not exactly socially smooth/subtle when I like a guy (as you may have already guessed with this email). But the fact that he never comes up to me and starts talking makes me wonder: Is it true that if a guy really likes you, he'll come up and initiate conversations? No matter how awkward he is? Even if you're with a bunch of your friends? I don't know if I'm just imagining things with the eye contact crossing the hallway to walk nearer to me (when we're going in opposite directions) but I don't want to get my hopes up. And as an unbiased guy/dude/fellow awkward turtle, I figure you'll give me the best advice!
Okay, woah, for starters: it's definitely not true that a dude who likes you will approach you no matter what. Many of them will fail to approach you even if the stars align and the situation is exactly ideal in every way. There are dudes who will choose to jump out the window and onto a cactus if you catch them gazing longingly at the back of your head.
For what it's worth, my Shy Idiot progression worked like this: freshman and sophomore years, I wouldn't have approached a girl even if she had given me the perfect excuse (say, a text that said "Help, Jono, I need CPR! PS I love you"). Junior year I was outgoing enough to accidentally communicate my interest to girls, often without realizing I was doing it, perhaps through the ancient rhythms of my people. Senior year I was actually able to say things like "Hello I like you" which typically resulted in responses like "OK go away." My point is, the way dudes behave is going to depend on how comfortable they are with these situations, and that changes over time.
The eye contact and walking close to you are definitely signs that this dude is into you, though. Here's a list of similar signs, along with ratings of how reliable I think they are.
You catch the guy looking at you.
Once can be a coincidence, but if you catch him looking at you more than that, you either 1.) constantly look ridiculous or 2.) he enjoys looking at you. Ask yourself: are you wearing a cape or something? If not, he's probably into you. The only other situation in which you'd constantly be catching his eye is if you were both in a cartoon and his head frequently exploded.
He often walks close to you or sits near you.
You're probably not imagining this. This one isn't guaranteed—a dude who is into you won't necessarily hover around you—but it's unlikely to be a false positive (that is, a dude who is always hovering almost certainly does like you). There's really no other reason for this behavior; even if he did just like you platonically, he'd probably be direct about it instead of lurking around in the background.
He raises his eyebrows at you.
This, the facial expression that says "I am interested in the thing that is happening," is not something people do unless you are interesting them with your interestingness. Still, it could easily just be a friendly thing or a non-flirty expressive behavior.
He teases you.
Within reason, of course. There's a big difference between "LOL, your hair looks like a bird nest! Ha ha just kidding I love you," and "LOOK, IT'S JABBA THE HUTT." Generally, though, it's a socially safe way to talk to (or at) you without risking any kind of rejection or betraying any delicate emotions. It's the same idea as when little kids who like each other instead choose to shove each other and pull each other's pigtails. Well, that, or kids are jerks, I guess.
He preens (fixing his hair, dusting off his clothes, etc.).
This unconscious (or conscious) gesture says "I'm trying to look good around you." Some people do this constantly and reflexively because they are short and Polish and their shirts often make them look fat. Granted, my sample size for this observation is "me," but I'm just making the point that sometimes preening is just a meaningless behavior and not a sign of interest.
He's nervous, he blushes, or he generally acts like an idiot.
Someone who often seems flustered around you probably likes you. This is especially true if someone gets double-flustered when he's called on it. If he does like you, and some onlooker is like "Haha, Dude Boypants likes Girly Girlington!" and he's like "Buh... bluh... blubber?" and continues blubbering thusly, then his loss of composure indicates that he has something to lose here. Think about it: if someone asked you, in complete seriousness, if you were completely in love with someone you completely weren't, you'd laugh, right? The notion would be laughable. Or at least you wouldn't lose your mind and go "I'M AREN'T, SHUT UP!" and turn the color of a stop sign.
Anyway, I'm almost sure this dude is into you, but it seems clear he's never going to march up to you and ask you out. At best he will march up to you and ask what time it is and then march rapidly away. So you may need to give him some indications of your own, until he gets more comfortable around you. Luckily, some dashing, mysterious young man seems to have written a post about this very thing.