When you find a thread that you would like to follow, but have never posted in, subscribing to the thread will help you do that.
A perfect example of a thread that almost everyone may want to subscribe to is ResumeSpeed's
Complete List of All TSB's thread, so you never miss out on another update.
To subscribe, click "Thread Tools" just above the first post, then click "Subscribe to this thread".
This will add that thread to your subscribed threads list and you'll receive notice when there is a new post.
To check for new posts in your subscribed threads:
You can access subscribed threads whenever you wish from "Quick Links" on the Nav Bar... All of the titles that are bold in the list contain new posts since your last visit. To unsubscribe, simply place a check in the "instant" box to the right of the title and scroll down to the bottom of the page to select "Delete subscription"... if you have a number of threads to manage, you can handle them all at once in this screen.
To receive an automated notice for new posts in your subscribed threads:
One time only, go to "User CP" on the Nav bar - click "edit options" - scroll down to the 2nd module "Messaging & Notification - scroll to "Default Thread Subscription Mode" - set to "instant email notification". This will also subscribe you to any thread in which you make a post.... again, you may unsubscribe at any time.
The system will now send you an email when there is a new post in that thread... you will only receive one notice, despite the number of posts, until your next visit to the forums.