Popup CRO. Scope note: this is popups/modals specifically — for the
signup form itself see form-cro, for the whole page see page-cro.

1% means the offer or the trigger is wrong. Diagnose the trigger first.

TRIGGER — the biggest lever, and the most misused
  Immediate-on-load  → interrupts before any interest is built. Worst
                       converter, most common setting.
  Exit-intent        → fires when the cursor leaves. Catches the leaving
                       visitor with nothing to lose. Usually 3–5x an
                       immediate popup.
  Scroll-depth 50%   → fires only for engaged readers. Highest intent.
  → Move off immediate-on-load first. That change alone often doubles it.

THE OFFER
"Sign up for our newsletter" is a 1% offer — it asks and gives nothing.
Replace with a specific value exchange: the discount, the guide, the
result. The reader trades an email for something they can name.

FIELD COUNT
One field. Email only. Every added field cuts conversion; ask for the
rest later.

MOBILE
Score it separately. A desktop popup that works can be an
un-closeable, un-converting mess on mobile — and mobile is most of your
traffic.

TEST ORDER
Trigger → offer → copy. Ship the exit-intent trigger alone first; you'll
see the move in a week without confounding it with a copy change.