If you don't know AASHTO, and don't deal with bridge design, skip the bridge questions if they aren't general engineering questions. It is that simple.
Of the 20% bridge, some questions will be AASHTO-specific, but some will be more generally applicable to any structure.
I took two tries because I tried to use my well-tabbed AASHTO manual to find simple answers. I had also had a bridge design course in grad school within three years of the test.
Skip the bridge and learn steel, concrete, wood, and masonry. Focus on how loads are applied and how they are distributed. Look over minimums, like reinforcing in concrete and masonry, limit states, anchors, and the other things you do everyday as a working structural.
Tab the crap out of your references well before the exam and USE the tabs in your daily work. The exam is not the time to figure out which info is in which tab.
Yes, you need to know what is between the tabs, but you need to be able to find information quickly.
Answer all of the questions, but don't waste time trying to find answers to things you do not know. I find it easy to go back and look over the questions which you skipped if you leave the answer blank - but be sure you skip the answer and do not get off one space (the right answer in the wrong spot is still wrong). IF you have time, go back and attempt the questions you skip, otherwise, at the 5 minute warning, simply go back and fill in answer "C" or "B" in all of the blanks.
And don't ever change an answer unless you have proved yourself wrong elsewhere in the exam. I always end up changing a right one for a wrong one if I make an unsubstantiated change.
Again, skip the AASHTO-specific bridge questions.
I'd probably not even take the book if I had it to do over (which I don't). SE II, anyone?