I released it in the newsletter each time. Sent it directly to each person on the list, some of whom shared it on linkedin/twitter. The 2nd got a bigger pop because of a larger newsletter base. I also sent it to 50 journalists who cover the industry.
Hang on a second... You wrote:
"The single best growth tactic I have for newsletters is to create a Top 100 of your industry list."
So you created a top 100 list and then... what did you do to gain 250 and then 700 subscribers?
I released it in the newsletter each time. Sent it directly to each person on the list, some of whom shared it on linkedin/twitter. The 2nd got a bigger pop because of a larger newsletter base. I also sent it to 50 journalists who cover the industry.
Nice! There's a vanity element to this, in addition to being incredibly useful.