The city's biggest flea market is hosted the first weekend of each month in and around a gigantic warehouse in the industrial area of NDSM in Amsterdam Noord. I love to snuff around the hundreds of stalls to find unusual props. Taking the boat to cross the IJ and leaving the old centre behind is very refreshing. Make sure to also have a drink in Noorderlicht while the sun sets.
OT301 is a cultural centre in the former building of the Film Academy at the Overtoom. It’s a good place to get drunk, watch a movie or to eat. It's not too expensive, like most other places in Amsterdam, and the ambience is good.
A really lovely restaurant with terasse with lots of sun hidden in the west and close to Erasmus Park. It is a place where you will a lot of locals catching up. The food is always great and there is a super cosy and friendly atmosphere. The kind of place you actually want to keep a secret so don't tell anyone! ;)