Should I buy an Eurail pass?

Only if you plan on traveling by train every 2-3 days. If you stay put for a week at a time, buying individual point-to-point tickets is almost always cheaper.

Look for 'lavanderia self-service' shops. Expect to pay 5-8 euros per load. Do not use your hotel or hostel laundry service as it is usually 3x the price.

How to plan a backpacking route through Europe

Focus on a single geographic region—like Central Europe or the Balkans—to avoid spending all your time and money on trains. Prioritize two to three days in each city to balance exploration with the exhaustion of constant transit.

Define your anchor cities. Pick one city to fly into and one to fly out of. Do not attempt a 'loop' if you have less than 21 days; instead, travel in a straight line to maximize your time on the ground.
Use the 'Rule of Three'. Commit to staying in each location for at least 3 nights. This allows you to unpack, find a local grocery store, and actually see the city rather than just the train station.
Connect with regional rail. Use Omio or Rome2Rio to compare trains, buses, and budget flights. For Western Europe, book trains 30 days in advance; for Eastern Europe, use FlixBus, which is often 50% cheaper than the train.
Limit your border crossings. Cross borders no more than once every 5 to 7 days. Frequent travel days kill your budget and your energy levels.

Should I buy an Eurail pass?: Only if you plan on traveling by train every 2-3 days. If you stay put for a week at a time, buying individual point-to-point tickets is almost always cheaper.
How do I do laundry?: Look for 'lavanderia self-service' shops. Expect to pay 5-8 euros per load. Do not use your hotel or hostel laundry service as it is usually 3x the price.