However, several things.
1) Do you research; search the names of the providers online and read recent forum posts about them before subscribing.
2) Learn how to pay for the services privately but legally.
3) Use anonymous proxy websites that scrub your computer's information from the browser to access and post to your site(s).
4) Don't permit unmoderated posts on your site. (Go to Poynter dot org and sign up for their media law web course.)
5) Create a terms of service that looks like something out of a legal research book to protect yourself.
6) Check out other similar sites terms and conditions for accepting subpoenas and requests from law enforcement and governments.
7) Make sure the service you're using doesn't tolerate and illegal activity (like warez, spamming, pornography, etc.) on the one hand but allows you to post the content you write on the other. You'll find a lot of those.
Also, have a virtual phone number, anonymous email address and make sure any content you upload is completely scrubbed of information from your computer like the name of the creator and the date, local URLs, etc. Protect your sites code with software that hides it. And make sure you've covered EVERY privacy related track you can before you go live. After you launch, keep checking to make sure you're covering your tracks. I hope this all helps or at least gives you a starting place.