Please observe the following...
  1. Use your UCA Cub Account. Doing so keeps everything on the up-and-up, and many professors just won't open/answer emails from a personal account. Certainly, your UCA email address makes a better impression than your personal email address might, and maybe or says more about you than your professor really needs to know. Certainly, these addresses look a lot more like spam than email from a UCA address.
  2. Use the subject line to indicate the class you are in and the reason you are writing. Don't leave it blank. Don't type, "Hey." Instead, try 8am MWF Essay Assignment or 22480 Midterm grade or Unexpected Absence from 8 TR Class.
  3. Email is a form of correspondence and so the usual rules apply. Your email should contain a Salutation (Dear Professor Plum or Ms. Mustard). "Sign" the email with the name you are known by (and which is sometimes different than the email address).
  4. Please remember to use common courtesy, and be aware of the tone of your email.
  5. Proofread the email. It's very bad form to send an email that contains spelling errors. Don't ever use texting shortcuts (u for you, etc.).

...or run the risk of your email being ignored.

With thanks to Michael Leddy's post at Orange Crate.
Related: 5 Rules for Better Letter Writing.
More suggestions from Wikihow.
And then there's this.

EEECO (Easter Egg Extra Credit Opportunity): Send me an email, telling me something about yourself while observing the suggestions above, and I will award you extra credit points.