This excellent opt-in form example comes from GoodUI, conversion-rate optimization & testing specialists known for their "DataStories" publication, which...View More highlights certain tests they've run & the big takeaways they got from them. The first time I landed on their page, I was impressed by how they used an animated red bar to draw attention to their opt-in form & then followed up several seconds later with a wiggling animation of the form, drawing attention back to it. They've publicly stated that these additions (they didn't have them previously) helped bump their conversion rates. The red bar animation occurs upon arrival & the wobble happens around 10 seconds later (note: the GIF below was shortened so there wasn't a long lag).