First time doing a landing page. What did I do wrong? What can I improve?

Since you asked

• Colors
• No social proof
• No incentive/example
• No trust factors

Good luck!

3 suggestions

1. Color
Gradient are messy. Pro-designers maybe know how to use it. For the rest of us, better to use basic colors. If you apply this suggestion, go for a not over-aggressive background. White and black are the typical choices. Other colors can work too. But a full red background is probably too much.

2. Stay above the fold
Displaying the whole form above the fold increases the conversion rate. In this case, with a very short copy, the need to scroll down looks like a mistake.

3. The copy
I prefer to start a landing page with a headline about the problem. Ask the reader: "Do you have problem X?" Then it's easies

• to get his attention,
• to write the rest of the copy.

In the headline you can say something like: "Is writing a pain also for you?"
Then in the subtitle you promise the result: "Develop this skill and become a pro"
And at the end you present your solution: "Subscribe to Online Writing Bible to receive the best writing advice, tools and resources. I will curate them for you in a weekly email".

Does it make sense?

Not bad for a first time landing page! Strong headline, mobile friendly, simple page with good call to action.

Some suggestions:

Headline: "Start writing like a pro." You could just say "Write like a pro" to cut down the number of words.

Copy: "I'm curating in one place..." Switch to starting this sentence with "You" instead of "I". People care about what they get out of it, not what you are doing. Perhaps something like: "You can get better faster with access to this curated treasure trove of the best writing advice, tools and resources."

Call to Action: "Submit" on the button is default and boring. Put right on the button "Activate Early Access" or something similar that shows the value the people are getting by submitting the form.

Design: The red gradient background is distracting to me, and harsh on the eyes. It also hides the phrases that appear to be highlighted. Can you change the background? Here's a quick mock up of a dark theme idea: