The job interview is over. Now, how do you follow up?

FORTUNE — Dear Annie: I’m graduating from college at the end of May and have already been interviewed by two companies that might want to hire me, with two more interviews (at different employers) scheduled in mid-March. I could really use some guidance from you and your readers on how to go forward after these meetings. For example, I sent thank-you notes by email to the hiring managers I’ve met so far, but a friend says a handwritten note would have made me stand out more. Should I do that next time?

Also, how soon after the interview is it acceptable to ask whether I’m still being considered for the job, and how often should I get back in touch if I don’t hear anything? I’m trying to seem enthusiastic but not desperate. Suggestions, please? — Newbie in Nashville

Dear N.N.: Great question, and one that plenty of seasoned jobseekers puzzle over, too. Dan Black agrees with you that the line between being persistent, which shows initiative, and being pesky, which is just annoying, “is a very fine one. It can be hard to locate.” Black is director of recruiting for the Americas at EY (formerly Ernst & Young), and current president of the National Association of Colleges and Employers (NACE). This fiscal year, EY plans to hire about 10,600 people, including some 6,300 new grads like you, a 5% increase over 2013 in campus hiring.

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The time to get a feel for how soon you should hear back from the employer, he says, is during the interview. “We always try to tell candidates when they can expect to hear from us, and how to contact us with questions, whether that’s by email or by phone,” he says. “But if the interviewer doesn’t mention that to you, you should ask, at the end of the conversation when you have a chance to ask questions.”

Dan Finnigan, CEO of social recruiting platform Jobvite, agrees. “It’s also critical to abide by whatever the answer is,” he says. “If the recruiter or interviewer suggests contacting them by email, for instance, don’t call on the phone.” Timing matters, too. “If the employer mentions that they expect to make a decision in a week, then follow up within that week,” he says. “Otherwise, ask if you can get back in touch within two weeks” about whether you’re still in the running — and then do it, or “they will remember that you didn’t follow through.” A timely follow-up “is never seen as pesky,” Black adds.

You did the smart thing by sending thank-you notes. “HR people and hiring managers expect them as part of the etiquette of the process,” notes Black. “And you certainly don’t want to be the only candidate who didn’t send one.” He recommends keeping it “short and sweet, reiterating your interest in the job and, if possible, referring back briefly to some area of common ground that came up during the interview.”

However, whether a thank-you should be handwritten or via email is, as you’ve noticed, a point of debate. On the one hand, a handwritten note “will get you noticed, because so few people send them anymore,” says Finnigan. On the other hand, though, email is probably fine, because snail mail missives “aren’t as timely, and some people don’t read their mail.” A handwritten note could also make you seem old-fashioned, or as if you aren’t on top of technology, he says. The important thing, in his view, is to send a thank-you quickly — preferably within 24 hours, while you and your resume are still fresh in the interviewer’s mind.

What if, as sometimes happens, you follow up after an interview (or more than one) exactly as the employer suggested — and you still hear nothing? This is where the line between persistence and peskiness can be especially foggy. Companies often take up to two months to fill senior jobs, so hearing radio silence for a few weeks may simply mean they’re still interviewing people.

But for an entry-level job like the ones new grads usually get, “never reach out more than twice if you hear nothing at all after two weeks or so,” Finnigan says. Even then, try to have a believable pretext, like a blog post you just wrote that is relevant to the job you applied for: “You cross the line into peskiness if you have no real reason to get back in touch except that you haven’t heard anything.

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“If you happen to know the interviewer’s cell phone number, don’t use it to call or text them,” Finnigan adds. “It’s creepy.” Likewise, although twenty-somethings are famously comfortable with social media, he says, “do not attempt to friend interviewers on Facebook.” Some job hunters, especially inexperienced ones, see moves like that as merely friendly gestures, but interviewers are more likely to feel as if they’re being stalked.

One more thing: If you never do hear a yea or nay from some of the people who’ve interviewed you, don’t take it personally. “You have to accept the reality that many people have a hard time delivering bad news,” Finnigan observes — so they just say nothing. But, says Black, even if you’re disappointed (or even angry) with the treatment you get from employers, try not to burn any bridges.

“You have to be professional about this process, because you’ll run into some of the same people later on in your career,” he says. “You never know which of them will be turn out to be important to you.” Good luck.

Talkback: If you’ve interviewed for a job lately, how did you follow up? If you’re a job interviewer or hiring manager, where do you draw the line between enthusiasm and desperation? Leave a comment below.