First, welcome to PPT =D
Secondly, I really don't have a problem with keeping up. I don't visit ever single forum. Some I just don't have much reason to be in, like the Anime board.
And with the ones I do go, I usually go to the same ones in the same order everywhere. I start at the top and read any new posts in Announcements, and PPT Discussion & Questions. See, everytime you log in anything that's been posted since your last visit will be marked with an orange icon:
as opposed to a plain one:
The orange icons are a good jumping off point for which threads to read first.
After Announcements and PPT Discussion & Questions, I jump back toward the bottom and read Miscellaneous Discussion and Miscellaneous Polls.
Within each boards, I read new threads from the bottom up. Once I'm satisfied that I've read everything I want to read in any specific area, I move on to the next one. I always save Neopets for last, as it's the most active forum on PPT and usually takes me the longest to read.
I'm quite an addict of the unread posts icons, because if I can keep track of what's been posted since my last visit, then I feel like I can't possibly've missed anything. I don't think anyone here reads every single thing, because it would just take too long.
My advice: take your time and don't try to do everything at once. Eventually you'll probably get into your own little pattern for reading PPT. I'm sure you'll love it here.