Even if the flight is on time, you should still show up at the airport 1-2 hours before the plane leaves, since you have to (how long you have to wait depends on time of day and how many other people are in front of you, so it can 45 min. or 10 min.)
(stand in line and wait) at the check-in counter, so you get your boarding pass (and possibly check your luggage)
(stand in line and wait) for the security check (you walk through a metal detector of some kind, are wanded down possibly) *
(sit and wait) till your gate is called
(stand in line at the gate) to board once the flight is called for boarding
(possibly get on a bus to be taken to the plane, or walk through a tunnel directly connecting the gate to the plane)
Depending on how much/ little luggage you have, it’s therefore a time-saver to have only a small carry-on bag and no checked luggage.
Still there’s lot of waiting time, so a crossword journal, thin book, electronic device that you can open and use while standing/ sitting and waiting will make things bearable.
And when you arrive, and have checked luggage, you have to wait till the baggage handlers unload the plane, drive the luggage to the building and load it onto the carousel, which may take up to 45 min.
Depending on where the carousel is, you get off the plane (again, bus or tunnel), get in line for passport control, and then look for the carousel, and your luggage is already there - or you wait first for your bag, and then wait again in the line for luggage control.
Customs in those European airports I have seen is split into “nothing to declare” =Green lane and “to declare” = red lane. Depending on what you are taking with you, you need to use the correct lane. Customs can do spot checks in the green lane. Most people think of alcohol and tobacco over the allowed limit (or illegal drugs, which can’t be declared, since they are illegal), but from watching docu soaps, there are lots of things either forbidden in some countries, or you have to pay tax on it. E.g. bringing homemade food into a country may be forbidden for health reasons (or in California, to protect the agriculture from diseases and parasites). Bringing cheaply bought electronics may require additional tax. You should try to find the homepage of the customs office for the country you are entering; and, if you want to do a lot of shopping during your stay, also check your own country for your return.
As for the toilets: the ones in the aiport should be in better condition and also bigger than on the airplane itself; given the amount of time waiting in the airport vs. flying, you probably should go on the ground before boarding instead of in the air (as much as that can be controlled).
- A tip to make the security check easier: wear little metal, and know where the metal is (key, belt, but also zippers!); wear shoes you can easily slip on and off; use a little pouch or similar to have boarding pass and passport at hand immediately.