Agree with David, anyone who is motivated enough to steal/scrape your content will be able to do it. If it's out on the web, then it's up for grabs... Kindle is not a foolproof way as well and there are various options to grab your content from Kindle given the right motivation. Most prevention steps (e.g. JS codes on your site or DRMs on e-readers) can mostly slow people down but not more.
If you are motivated enough to chase down those who steal your content, there are a few classic tricks that will help you track the offenders, like planting typos, hidden HTML tags, watermarks on images and more.
There are a few free/cheap tracking solutions for text like copyscape, plagium and others. you can also set Google alerts (which is not scalable if you have a lot of content) and there are few more expensive/custom solutions for enterprises who are willing to pay. Images are a different story (from a tech stand point) but similar solutions would allow you to find out where your images have been used, from Google reverse image search to a few custom tools that work at scale. there are a few video detection solutions but not cheap/free ones to the best of my knowledge. Books are actually easy to track on the open web (i.e. if someone offers them on his site and doesn't use passwords or compression/encryption).
Acting against the offenders is another story and it can get quite complex and expensive given the platform they use to host or re-distribute your content and the legal jurisdiction. many people just go to Google and ask to delete the violating URL/site from their index.
There are plenty of resources on the web with specific tips and tricks (as well as legal advice on how to mark your content as protected, etc.), you can start with the kissmetrics blog. context is important so you should specify in your search the type of content you want to protect (blog, book, image, audio, video, etc.).
From your question, it sounds like you are planning on offering some of your content behind a paywall. the paywall should allow easy access only to users who pay (or have been otherwise authenticated by you) and will make it harder for bots and auto scrapers to grab your content, it will not prevent paying users from copying and re-distributing it.
In reality, it mostly makes sense to go after violators in case your content has inherit value (e.g. a transaction is required to access it), most bloggers and small publishers (with free content) take the few basic prevention steps but only a few go after violators. larger companies that have more resources tend to be more agressive against violators.