The first pavilion, which I’ve visited, was a Russian one because I’m Russian. There you can try delicious Russian food.
Next to Russian pavilion is Estonian one.
The ticket you can buy right at EXPO (when you get off the metro or train in a ticket office) and it is better to come a bit earlier (around 6 p.m.), because there will be a super long line to get in the EXPO in the evenings and especially at weekend, so be ready to be patient enough to wait and probably to get inside around 7:30 p.m.
If you are in Milano, I would suggest visiting an open-air museum, which is the Monumental Cemetery of Milan.
This place is really impressive, especially if you go there on a dark rainy day. However, I had no depressive feelings about, maybe because I’ve been there on a nice sunny day.
There are so many different and beautiful sculptures, so it’s almost impossible sometimes to consider as a cemetery!
If you are interested to visit, you need to know that they close the gates 30 minutes prior to closing time and Monday is a day off. Opening hours from 8 a.m. till 6 p.m. For me, less than 1 hour was enough, but I’d like to come back.
I would recommend visiting the roof of Duomo even if you are not a fan of touristic places. The experience is unforgettable!
There are two ways to go up — by stairs (11 euro) or lift (15 euro) with included Duomo museum, archaeological site underground Duomo and Duomo itself, of course.