There are two ways. One is in your profile settings which I am not super familiar with. Second is when you are in the thread look at the top of the first post and find thread tools. Click on it and it will bring up three option and the last one is to subscribe to the thread. This will allow you to access the thread with out having to search for it. To gain access look for the quick links tab and you will be able to pull up the threads you have subscribed too.
I receive messages when someone quotes me or a thread I have subscribed too is updated.
Hope this helps.
R/
Will