First, see if the ticket line is not full of peopl...

First, see if the ticket line is not full of people "who can't speak English". There were many tourists who can't. The Cashiers will still sell them guide books and ask them to give the "obligatory" donations to the Tower upkeep. You can tell a tourist group that needs help - a lot. We waited 40 minutes just to get 2 tickets while the other lines move along.
Second, TAKE THE YEOMAN TOUR. They are very funny, informative and authentic. Last tour is, 15:30.
THIRD, make the Royal Crown Jewel your last stop. The other buildings like the White Tower, Bloody Tower, etc. are more interesting and needed more time to see. The Chapel is interesting. Ask the Yeoman where was Anne Bolyn buried. It is not in the Sarcophagus.
Fourth, the Cafe/Canteen serves good food.
Fifth, always bring an umbrella and wear a good walking shoes. You will climb a lot of stairs.