What kind of lead magnets worked well for increasing the subscriber count of your newsletter?

In the second half of the year, I wanted to use some kind of lead magnet that I sent to people in exchange for their email address.

My questions are for observing purposes:

• What type of lead magnet did you use to grow your newsletter?

• Where did you promote the lead magnet? (social media, landing page, format, paid promotion?)

• How many signups did it get you?