Documents
While we all know to check to see if we need a pre-Visa, or may obtain a Visa Upon Arrival, it is often easy to forget to carry the Name & Address of the first hotel for Entry Documents.
It is important to have the name of the first hotel, especially if you are entering the country at a lesser known Point-of-Entry, than say, the nation's capital. Local Customs Officials can be inexperienced with extensive Globe-Trotting, International Travelers.
Photography
DON'T DO IT! No matter how excited you are to be in your new country, photography & filming is STRICTLY PROHIBITED in all airport Customs, Immigration, & Security Clearing Areas.
Always wait until you have cleared customs and are on the outside Terminal before taking photographs.
Prescription Drugs & Vaccination Cards
Be sure to check which Prescription Drugs are allowed in the countries to which you will travel. And, do not forget official proof of Vaccinations.
Some countries, such as the Republic of Uganda, offer Yellow Fever Vaccines at Entebbe International Airport, if you don't have your Vaccination Card. But the shot costs money which must be paid in US Dollars & do you really want to start your Safari with a shot in the arm? And, this is rare, you can actually be quarantined or even "Denied Entry" without official Vaccination Cards.
And, once "Denied Entry," it can be nearly impossible to gain a new Visa. This is one case where forgetting documentation can go on your "Permanent Record"!
Don't forget your Vaccinations Cards & check on what Prescription Drugs are allowed!
Bathrooms & Bottled Water
Who knows how long it will take you to get through Customs, Immigration, & Security when deboarding a flight? Go to the bathroom before the airplane lands & be sure to carry a bottle of water with you.
While it is easy to assume this is only advise for airports in smaller regions, recent reports have clocked Heathrow International Airport Security lines taking up to four (4!) hours.
In addition, you may not always be allowed to get out of line to go to the bathroom and some airports may not have air-conditioning. Combined with dehydration from the plane, it best to be prepared by going to the bathroom before the airplane lands and having a bottle of water for the lines through Security.
Cellphones
Do not bring out your Smart Phones / Cellphones, once you have deboarded the airplane, until you are COMPLETELY through Customs, Immigration, & Security.
Once the Pilot has announced you can take your devices off of "Airplane Mode" & before deboarding, that is the time to make any telephone calls, send text messages, or message family, friends, or awaiting parties.
Once you have deboarded & are off of the airplane - DO NOT TAKE OUT YOUR CELLPHONE UNTIL YOU HAVE LEFT CUSTOMS, IMMIGRATION, & SECURITY AREAS & ENTERED THE MAIN TERMINAL!
I can not stress this enough. This has become a hot-topic, flash-point issue. One of the reasons for this is the recent number of high profile cases of Airline Passengers getting into arguments with Customs & Immigration Officials and deciding it would be a "good idea" to record these arguments.
If Customs, Immigration, & Security Officials see you on your Cellphone, in any airport in the World, they have every reason to believe you may be recording or taking pictures. This is simply a basic Security Issue.
Need the time? Look for a clock - there will be one somewhere. Need to communicate with someone? Do that before you deboard the airplane. Just so darn excited to be there you can't wait to take a Selfie? Wait. No Selfie is worth getting in trouble with local Officials.