Pop up window are still effective ways to get subscribers. Especially in niche markets.
Creating pop ups on your website is as easy as a pie. There are however a few different type of pop up windows you can use.
The pop up window on exit, which pops up after you leave a website and the pop up window on entry which obviously pops up when you first go to a website.
You can do a web search to find tons of pop up programs.
I prefer the pop over that can’t be knocked out by pop up killer. So when someone visits your website they get interrupted by your pop up message you want to get across immediately, i.e. asking them to subscribe to your newsletter, etc.