Only use your student email! This is related to FERPA (legal things). Also, your gmail or whatever might go into spam.
Check your instructor's syllabus for their contact preferences: some want to be emailed directly, some only want you to contact them through D2L, etc.
Check the syllabus, too, to see if your question has already been covered!
Be proactive! For example: Not going to make an assignment deadline? Email before the due date, not after.
Subject line: do have one. Be descriptive. "Help!" isn't a good subject line. "Can't submit assignment to dropbox" is better.
Greetings! "Hello, Prof. Lastname" or even "Dear Prof. Lastname" are great choices.
Bad choices are skipping this entirely (at least the first email) or "hey, [question]."
Mention what class you're in -- it's very helpful! If you don't know what your section number is, at least state that you're in the MW 10 a.m. class.
Provide explanation. This goes along with being proactive.
Is something broken? What is it, and what have you tried so far to fix it or get around it? "I rebooted my computer and it still didn't work, so I've submitted a ticket to OTS and I'm working with them to get my assignment in. I just wanted to give you a heads up."
Is there something going on in your life that's causing problems? You don't need to provide every gruesome detail, but at least mention "health issues" or "a death in the family" or "scheduling issues with work." Contact as soon as you're aware of the issue.
Are you unsure of assignment guidelines? First, check the syllabus, class schedule, D2L, announcements... and say so. Be specific in your questions. "You said to cite our sources but I didn't see a particular style to use. Are we using MLA?"
Bad choice: "I'm confused about the Career Exploration assignment. What am I supposed to do again?"
Gracious: A Practical Primer on Charm, Tact, and Unsinkable Strength by Kelly Williams BrownGraciousness is practicing the arts of kindness, thoughtfulness, good manners, humanity, and, well, basic decency. It's about approaching the world with compassion, conviction, and self-confidence--and it makes all the difference, whether you're at a Fancy Schmancy Intimidating Work Occasion or at the convenience store. Gracious provides tips to help you deal with the people and circumstances that challenge all of us (pushy relatives, internet trolls), and thoughtful discussions on being the highest version of yourself. Graciousness, at its heart, is the ability to be truly present to the humans around you, to face the world with a generous heart and a core of strength that's never corroded. Even when you get rude comments from Internet strangers (hot tip: you don't give a lot of credibility to someone screaming obscenities at you on the street, so why do it online?) We can't control the world, or other humans, or even how we feel in a given moment. The only thing we can control is our words and actions, and when we act deliberately and with kindness, it makes everything better.