Beware, there is A LOT of walking!! I managed over 50,000 steps in 2 days.
Ok, so here are my tips:
I suggest taking public transport if you are coming from further away as you are not going to want to drive after a days walking.
If coming from Abu Dhabi, the Expo rider is stationed at Abu Dhabi Central Bus Station, bus terminal, #313 and at Marina Mall. First bus departs at 8:30 AM and run every 30 mins on the dot. They stop at the Expo Mobility entrance and this is free, travel journey is approx. 2 hrs+.
Food is not allowed to be bought into the expo. However, a water bottle is a must. There are drinking stations to refill your bottles. These are touch sensitive, just put your bottle under the tap and it will turn on - don't panic as someone did. LOL. Of course restaurants will be packed and pricey, there are kiosks but the queues are very long so bring crackers to stave off that hunger while you go around.
Bring a sun hat, a face towel, and those rechargeable fans if you have one and extra face masks for changing.
Don't bring in too many things with you as baggage check is strict, like an airport, but efficient.
If you want to hit the big countries, go early before the queues build up, and then just go around to the smaller ones. Some pavilions take a longer time - some have shows, or if you're anything like me, I am really engrossed into some exhibits.
If you're coming from another emirate, choose a lodging near the metro for easy access if you plan to maximize your expo stay in the emirate. Metro fees apply.
There are some pavilions who do not stamp, so expect stamps at every stop. Also, its not a game to collect stamps BTW.
I suggest just follow the Ghaith Street as it goes around the big Expo building, ball looking like building, and just go at its branches so you don't get lost, like I did first day. LOL, or open your Google maps and type in the pavilion you want to see and it will direct you. The whole expo is mapped in Google maps and free WiFi is available.
The pavilions are GREAT at night, as the lights add magic, but they queues are horrendous. So if you're just sightseeing outside, yep go at night. But if you want to go in and really know, you'll need the whole day.
Pavilions close at 10PM, though the expo closes at 2AM and if you're really into splurging and having the most of the Expo, Rove Hotel is smack in the middle of it. Book a night, or two, and get your passes free for your entire stay. (look into that deal) ENJOY it, its history in the making for this country. Avoid being so pessimist and engage in unhealthy conversations because you've been waiting/standing too long... Their are volunteers standing there from opening until closing so treat them with kindness. They are doing it for FREE and for LOVE of civic responsibility. Learn from this! And be so proud you get to be part of it.