If you aren't from Europe there are two types of European transportation you might not fully appreciate. Low cost airlines (AKA LCC or budget) and trains. On the surface the two are similar enough to what you're used to. But they're so much part of today's travel in Europe that you really should understand what they provide and the potential pitfalls.
This post will deal with budget airlines. A later posting will deal with the rail system.
The three largest European budget airlines are Ryanair,Vueling (Part of the BA/Iberia family) and Easyjet. All three are best thought of as internet companies. Not only is it easiest to book your flights online but the best source of information is the airline's own website. The airline webpage will show you everything from the checking procedure to baggage allowance to special needs.
We should start with Ryanair the largest and best known. You may have heard of Ryanair or at least it's reputation. It's known to be a stickler for the rules. To a certain extent this is true but the issue you are unlikely aware of is Ryanair requires non EU citizens to get their boarding passes stamped prior to passing security. At the moment no other airline does this. The requirement to have your boarding pass stamped means you can't use only the smartphone app. When you arrive at the airport find the Ryanair desk. The staff will check your ID and boarding pass and stamp it. If you forget or if you decide to risk it expect to miss your flight. If it's not clear you'll need a printed copy of your boarding pass. Failure to print out your boarding pass will give you an introduction to one of Ryanair's most infamous feature. The expensive airport boarding pass.
The next thing to know is Ryanair is changing it's carry on rules. Starting January 2018 passengers who haven't bought priority boarding will only be allowed to bring on one small bag. 35x20x20 cm (14x8x8 inches) Don't be tempted to exceed this. Remember the infamous fees. Your larger 50x40x20cm carry on will be put into the hold for free. Make sure anything you'll need on the flight is in the smaller bag. Also avoid having any valuables in the larger bag that will be checked.
If you have bought priority boarding you'll also be allowed to bring a 55x40x20 cm bag weighing a maximum of 10kg onto the plane .
In either case the smaller 35x20x20cm bag must be put under the seat and not into the overhead.
Hopefully I haven't scared you too much. Ryanair's reputation is worse then it's bite. If you follow the rules which are all clearly laid out you won't have any problem with Ryanair. If you don't follow the rules you shouldn't be surprised when problems follow.
A couple of final points. Watch the airports. Ryanair has a habit of using secondary airports that you wouldn't expect. DO NOT go by the city names. Check the airport codes. Last point. In many airports they use stairs for boarding. If your seat is in the front of the plane use the front stairs . For those in the back half use the back. The same principle applies when leaving the plane.
Is in many ways similar to Ryanair. They have the same carry on sizes. Unlike the new Ryanair rules most people will be allowed to bring both bags onto the plane. The big difference is Vueling is part of the of the IAG group of airlines. The two better known parts of the group are BA and Iberia. If you're fearful of budget airlines this should give you something to think about. Vueling operates flights for both BA and Iberia. The relationship between these airlines means you can pay Iberia/BA prices and end up on a Vueling flight.
Vueling main hub is in Barcelona . They often have connecting flights via Barcelona. Pay attention when booking. Vueling offers both direct flights and connecting flight. Unlike what often happens with airline prices these connecting flights cost more then the direct flights and can have lengthy layovers in Barcelona.
The last large airline is Easyjet. Easyjet has a larger single bag for each passenger. 56x45x25cm. with no weight limit. Easyjet does require you to lift the bag into the overhead by yourself but there is no weight limit. When Easyjet tells you only one bag they really mean only one bag. That means no handbag or any other bag. If you have a second bag the flight attendant can require you to place it inside your carry on. Better to do it before reaching the gate.
With all three airlines prices on the most traveled routes can be quite economical if booked in advance. It's not unusual to pay more for a cab to the airport . All three airlines also have sales . The prices during sales can be less then an airport lunch.
The seasonal routes are the ones that can be expensive if you don't buy in advance. If your plan include trips to the Greek islands or other seasonal routes buy your tickets the moment you are sure of your dates.
They all have smartphone apps that today are quite good. Just remember the Ryanair warning to print your boarding pass. The apps allow you to pass security. Help you keep track of your bookings. Or to do the actual booking.
To end with think of short haul flights with in Europe like fast buses. Do not expect champagne. Follow the rules. Have reasonable expectations. They'll all get you to your destination on time and for very little money