This works well for me, but its probably quite white hat, maybe you can black-hat it up a bit -
Pretty simple, just make a twitter account, follow lots of people on it and you get a percentage of them follow back and you also get views / clicks etc from even the ones that dont follow you back.
Few things to keep in mind -
1.You want to obviously follow targeted accounts, so you can do this by looking at popular accounts in your niche and following their followers or followings - I found that often with following other peoples followers you get a lot higher follow back rate - because obviously those people are all following another account in your niche already, BUT when you follow a popular accounts followings - the people they follow - you get a lower follow back but you tend to get higher quality followers because popular accounts are following ONLY targeted accounts, whereas people that follow them are lots of other spammers doing the same thing you are doing.
2.Remember quality is better than quantity - lots of people used to work on follow back circles on twitter - follow for follow, and you could get thousands of followers, but whats the point when they are all doing it for the same reason as you? If you can get just hundreds of targeted followers then you can generate lot more targeted traffic.
3.Content on twitter is really important. The above works much better if you schedule up some relevant content, and maybe put something really viral as a pinned tweet. Then every account you follow, they get a notificatio, then they check out your timeline and they make a decision based on that as to whether they want to follow you back or not - so content is super important.
4.Tools. I think there are lots of twitter bots you can find to automate the above. If you want a paid option then manageflitter is really good online tool that can automate everything above for you. If you want a free option then there was a good thread recently about a chrome plugin that can pretty much do most of the above as well -
https://www.blackhatworld.com/seo/how-to-build-a-fanbase-off-a-twitter-dominator.974808/.
5.Obviously you can scale up the above and like I said - I am sure you can probably think of ways to gear this up: I am doing it pretty low volume and white hat but it definitely works.
6.Monetising - once you have the twitter account running then you can generate a lot of traffic from tweets - especially if you have a nice viral tweet pinned to your profile and it keeps getting retweeted, and from links in your profile etc.