How to write a first message

Your first message should include a greeting. It’s polite. Don’t go crazy, just say “hello.”
Your first message should be constructed of complete sentences.
Your first message should be at least 20 words in length.
Your first message should not comment on the other person’s physical appearance in any way.
Your first message and every message you ever send should be respectful and positive.
Your first message should not be generic. If it could be copied and pasted then it’s a bad message. Regardless of whether or not you took the time to type up a brand new message, if it’s totally generic the other person won’t have any reason to believe you didn’t just copy and paste it.
Your first message should start at least one conversation topic which relates to something the other person wrote in their profile. This shows the other person that you didn’t copy and paste your message, that you actually took the time to read the person’s profile. It also gives the person something to respond to. It’s also important to be specific:
Don’t say, “I also like coffee.” Talk about your favorite coffee shop - or the best cup of coffee you’ve ever had.
Don’t say, “I also love to travel.” Talk about a cool place that you’ve been to, or where you hope to travel to next.
Don’t just say, “I like Hemingway too!” Talk about your favorite book by Hemingway and why you like it. Don’t write an essay, but a few sentences is great. Or if you think that Hemingway was a bit of a prick, write about why you don’t like his work. But if you’re going to disagree with someone, make it a fun and respectful conversation.
Ask Questions. Ask a few questions - not the same question this person has heard every time. Don’t ask the most obvious question. Ask the second or third question you think of. (Make sure the question is respectful. If you aren’t certain if it’s appropriate, assume that it isn’t appropriate and come up with a different question). And don’t ask generic questions like “what do you like to do for fun?”
Don’t complain about anything in your first message. Don’t complain about how you don’t get many responses. Don’t complain about how frustrating online dating can be. Don’t complain about your ex.
Don’t write anything anywhere as near as long as this article. Unless you’re comfortable with the fact that most people won’t take the time to read a first message longer than a few hundred words. I personally wrote very, very long first messages for a while, because I like writing long messages/emails/letters and I wanted to avoid getting involved with a man who would find this tedious.
Don’t try to use lots of big silly words that you never actually use in real life. Write your message in your own voice.
Be yourself. Be genuine. Be earnest - it’s very Important.