What to do at the Phnom Penh airport?

It is a rare opportunity to fly to visit another country which is so different from our normal living day based on the condition, environment, standard of living, and even people. As part of graduation for my last four years at Pour Un Sourire d'Enfant (PSE) -- this non-profit organization helps and supports underprivileged students and poor families, I got an opportunity to intern at a well-prestigious and more than 100 years company based in Shanghai, China -- Henkel -- which has more than 30 branches throughout the world and its headquarter is based in Düsseldorf, Germany , having officially been recognized as the world's friendly branch. 

Gotten the visa and confirmed flight ticket, I had to prepare my 6-month luggage and had to come at least two hours earlier for flying preparation at the Phnom Penh International Airport, a well-known air port since the 1960s of King Sihanouk's regime, to make sure I had everything officially required for departure. 

Therefore, what would be the best to be considered preparing is to first be there earlier before time so that we could still check if we had everything needed. Frankly, we had to get into the departure working place to check in and check the luggage as they are a must-to-do responsibility; and for sure after having already checked in, we had to go to check the tax payment place before going up stair to wait for the departure. 

Once ready for above mentioned tasks, we had to go up stair for checking the passport and the portable luggage that we take along the way, then just go to the waiting place for departure. However, what we need to have is flight ticket and passport with visa so that it might not be making trouble for us.  Last but not least, we had to check our seat to make sure that we might not take someone's; otherwise, we will be asked to sit at the right place. Do not worry about this since we can find the seat number in a form, that we had already been asked and given at checking in place before getting up stair.