Had too many suggestions for @LevNovak so here is my spin-off
  1. Research Food
    These days there are endless resources for finding good restaurants. And the foot search for good food often leads to new adventures. I always check Anthony Bourdain, Bon Appetit and Eater. And ask friends! You should have a list of good places to eat. Dont need reservations made, but have an idea of where youd like to go. Everyone hates that feeling of wandering aimlessly trying to pick dinner while youre starving and cranky
  2. Plan your day around food
    Now that youve got places to eat, plan your day food first. Pick where you want to eat first and work backwards. Got a lunch place youve got to try? Find the museum closest to it and visit AFTER youve eaten
  3. Dont expect to like things on vacation you wouldnt like at home
    Do you hate museums? Dont go visit a museum on vacation.
  4. Split up!
    This is easier said than done, but splitting up from your travel party for a solo activity can be great. Gives you time to miss that person and you can chat about your day over dinner
  5. Book 2 hotels in the same city
    I like splitting up my stay into two hotels, especially in different parts of town. It gives you a different feel
  6. Book a nice hotel
    A nice hotel will make the trip feel 80% nicer. It doesnt have to be 5 star, but waking up in a place nicer than your home is the whole point of vacation, right?
  7. Keep moving!
    If you dont know anyone in a city to show you around, 3 or 4 days is the most youll ever need in one town. I promise.
  8. No rules
    If you find one bar you like and kind of only want to drink at that one bar your whole trip, GO FOR IT!
  9. Less is more
    It is always better to leave wishing you had one more day
  10. See the most famous thing there
    Its famous for a reason. And you need a picture of it to prove you were there
  11. Walk!