In our semi-post-Covid world, I've noticed students seem a bit more clueless about behavior with regard to professors and class. Here, I speak largely to undergrads; grad students are another kettle of fish. Also, this is a guide for students in North America. Other countries have other titles/expectations, but a goodly portion of this applies across the board.
I'm not sure how much some of the necessary informality of Covid led to these issues, as I'd witnessed these trends even before Covid, but certainly the lack of in-person education accelerated it.
So, here are some helpful dos and don'ts that will protect both you and your professors, and let you avoid pissing us off. It's offered without much cushioning, as sometimes bluntness is required. If most of this seems self-evident, you're all set.
1) READ YOUR EMAIL. Regularly. Which means more than once a month. Or once a week. Try once a day.
This is especially important in an online class, but also for in-person classes. Sometimes it's the only way we can get in touch with you, especially in larger classes, or if you have a habit of sneaking into class at the last minute and flying out the door at the end.
Failure to read your email could result in failure of the class because you missed important information.
2) SHOW UP TO CLASS. Attendance is not optional. With in-person classes, you do actually need to put your butt in a seat more than occasionally, or you'll fail. I can't guarantee you'll pass even with perfect attendance. But I can all but guarantee you won't pass (at least not my classes) if your attendance is poor. After teaching for 25+ years, I have the data to prove it too.
For some students, attendance was always spotty, but it's gotten notably worse. Some want Zoom as an option but you can't really learn (well) over Zoom. As things right themselves, I no longer offer Zoom options for class without a specific medical reason. Zoom is great for meetings, for international conferences, even for office hours. There are legit uses for Zoom. Lazy-attendance is not one of them.
Related: don't show up consistently (or even occasionally) late, or leave early--especially with no explanation. It may not be personal, but we (the professors) don't know that. Neither do the other students. If there was an emergency that called you away, common courtesy says to email the professor later to explain. Or if you were late, tell the professor why after class.
3) READ COMMENTS ON YOUR PAPERS (or other things you may turn in).
We expect you to learn from prior effort. I spend a lot of time commenting on student papers, both content and grammar. If you're not going to bother reading it, at least do me the courtesy of telling me so in advance so I can return minimal effort and not waste my time on you. If that sounds sarcastic, well, so does not bothering to read the comments your professor makes to help you.
If you can't find the comments (e.g., you're not sure how to see track-changes and comments), just ask! I'll be happy to show you. I'll also be happy to further explain anything in comments. I only can't be bothered when the student can't be bothered first. That earns my disdain. Otherwise, I am there to teach you.
1) ask for your professor's phone number. Nor should your professor ask for yours.
Exceptions: if you're doing some sort of field work or project or service learning, where texting may be important. But even then, it should be kept only to the project. You should not text your professor about other parts of your life...nor should they text you about theirs.
If a professor begins to intrude on your privacy, you should immediately contact your university's Title IX Office. Keep all texts. If they're calling you, try to record it.
Similar cautions apply to asking a professor's home address. Again, some exceptions, such as a whole-class event at the professor's home for an upper-division course. But generally, you don't need to know where they live, nor do they need to know where you live, at least not precisely. A general query is not out of order. Sometimes I do ask a student where they live when it comes to thinking about storms/snow, but I neither need nor want their street address, or even their street. If you wish to send them a card after class is over, take it to their mailbox in the department.
2) send your professor a friend request on Facebook or similar social media unless the professor has a public-facing account.
For instance, I have Twitter, Tumblr, and even a public Facebook account as a published author. But I also have a private FB account meant for friends and family. I do not allow undergrads on that account, nor do I (often) allow grad students, especially now that I have a public FB account. They simply don't need to know my family business (nor would they want to see 99 pictures of my cats and beadwork).
3) ask your professor to have a beer with you, or accept an offer from a professor to go drinking, especially one-on-one or just a couple of you. It can look very bad.
Exceptions: If it's a group event for the whole class and (of course) if the student is of age to drink in whatever country.
4) give your professor expensive gifts. (No, not even if you're wealthy. I'm not Sokrates and you're not Plato.)
Bringing them a chocolate bar or a coffee or some flowers is just fine. But anything over about $20/25 could look like attempted bribery, even if you mean it sincerely. And never offer or give your professor actual cash unless it's a reimbursement and there are receipts involved.
5) refer to your female professor as "Mrs." unless she specifically tells you to. "Ms." is not acceptable either, but it's better. For some students, this is a hold-over from what they were taught was polite in high school, but there are several problems with it in college.
First, your female professor is quite possibly a Dr., and calling her "Mrs." is reductive in a way calling a male professor "Mr." is not. Yes, due to sexism. I realize you probably don't mean it that way, but it can be perceived that way. "Mrs." removes your professor's individual identity as an expert in her field by not awarding her the title she spent a lot of time, money, sweat, and tears to earn (the PhD), and she may not even be married. It's a holdover from a more patriarchal world to assume she is.
What if your professor doesn't have a PhD? Not all of them do; one can teach lower-division college courses with an MA.
PROFESSOR is always safe. Notice I've been using it throughout this essay. Now, here is where different countries have different titling rules. But in the US, "Prof. ___" is always a safe form of address. If you want, you can err on the side of caution and use "Dr. ___." The person will probably tell you if they don't have that title, but they won't be offended if you use it. But you are quite likely to annoy your female professors if you call them "Mrs." and they're a Dr.
It's not being "uppity." That title took a lot to earn. Respect it. And "uppity" is another way men try to put women in their place.
6) call your professor by first name, either--unless explicitly told to do so. Some professors are uncomfortable with a title, but in general, do err on the side of politeness. Most of my students now are young enough to be my children. You don't get to call me by first name. (One of my son's friends in school used to call me "Dr. Ian's Mom," which I found funny.)
Hopefully, that will prove useful, especially for freshman and sophomores, as you start to navigate the wilds of college.