Decide Which Cities/Countries You Want To Go
Try to avoid including too many cities and countries in one trip. You can plan your trip prior using Europe Trip Planner to utilize your itinerary time. You might feel like you might as well cover more places while you are in Europe, but traveling between cities and switching hotels frequently gets very tiring after a while. And you end up spending a lot of time in transit, instead of actually spending to explore the cities you are visiting.
If you are going to be visiting multiple countries, you can consider including nearby countries in your itinerary (for example, Spain and Portugal).
Check If Need a Visa to Visit Any of The Countries
Book transportation from one city to another first (before you book your hotels). Travelling within Europe is relatively cheap with low-cost airlines. However, low-cost airlines may not have daily flights for the route you are looking for. So sometimes, you may have to rearrange your itinerary to extend an additional day in your previous city, until the next low-cost airline flight, to go to the next city, etc.
The airports for low-cost airlines are usually quite far away from the city center, so this means that you will be spending a lot of time going to/from the airport. So if you are short on time, then this is won’t be the best transportation for you
Getting Eurail Pass:
If you are visiting nearby countries in one trip (ex. France, Germany, and Switzerland), then the Eurail pass would a great way to travel within Europe
If you are visiting countries like Italy, where the train prices are already relatively cheap with Trenitalia, then a Eurail pass may not be necessary.
Also, if you are 26 or older, then the Eurail pass pricing goes up. So it may be cheaper to fly with a low-cost airline than to buy the Eurail pass.
Once your transportation has been booked/confirmed, book your hotel in advance
Many hotels offer early booking discounts and the accommodation cost adds up quite a bit when you are traveling for a few weeks, so best to take advantage of these discounts 😉