Some quick ones:
- Make value proposition clear. Just because they reached the signup screen doesn't mean they're already convinced to sign up.
- Show social proof on signup screen, such as customer logos or approximate number of users. Same reason as above.
- Offer SSO options. Google is especially popular
- Have an Obvious Next Step(tm)(R)(patent pending). Make it clear what the visitor is expected to do next by making that thing visually stand out, and muting (or removing) everything else. Notice in OP's signup screen that the background app preview is tinted, and the Twitter login button is the brightest thing, dead-center of the page.
- Have a product people want. This is a hard one. :)
I've sat at the signup/register/purchase screen so many times and muttered to my computer, "but I don't know what this thing does, why would I sign up?"
Playing coy was maybe cute in high school. Grownups communicate with each other, and nobody wants to do your job for you and pay you for the privilege (in cash, credit, or PII).
Three things I'm sure helped the signup rates, which others should copy:
- Low-friction registration using SSO.
- Glimpse of the product in the background.
- Let guests see and click on gated features. (Even if visitor clicks "Or try it instead" they still see "+ New Draft" button, which leads to the signup prompt again.)
I've tested these in other apps and found they significantly increase signups. The first because of low friction, the second because--I suspect--it shows the visitor what they're about to experience in just a few more clicks, and the third because it shows the guest what's possible and offers multiple chances to sign up.
Well done!