Look for this graphic:
It will link you to the first post you have not read (assuming you are browsing the board with cookies). This graphic shows up in most of the forum listings, and search results. Also -- at the top left area of each thread, there is a link that says something to the effect of 'go to first unread post'. That will take you down to the first post you have not read.
And, if all else fails, scroll down, looking for this graphic:
That graphic shows up next to each person's post, under their name. If it is there, it means that you haven't read that post, otherwise you will see:
