Whether you're dreaming of Greek islands or Spanish steps, Parisian cafes or Venetian piazzas, summer is the perfect time to visit Europe. Unfortunately, it's also the most expensive time of year to fly across the pond. Airfare prices are at their highest, crowds are at their largest and travel planning is at its most frustrating. But don't give up hope! Here are some easy ways to save money on your European vacation.See: Best Affordable Europe VacationsSitting on a bundle of British Airways miles? Always fly Delta Air Lines domestically, so you figure its international flights will do? Dismiss that thought. There are a number of budget airlines that fly from the United States to Europe that you may not be using, namely Icelandair, WOW air, Norwegian Air Shuttle and SATA International out of Portugal. Compare prices from the big airlines to these budget carriers and you may find sizable savings with the little guys.June is expensive, and prices peak for travel to Europe at the end of July, so avoid this time of year at all costs. Instead, wait until August or September. The last week and a half of August — and essentially all of September — are comparatively cheap; you could save about $300 just by waiting a month to go on your vacation.If you're already planning for next summer, consider May 2016 as well. Prices are just as low in May as they are in August, and that sweet time between spring break and the summer high season usually means fewer crowds.For most destinations, traveling midweek to midweek is the cheapest time to fly. Europe is no different: You can save a small bundle by departing on a Monday or Tuesday and returning on Monday, Tuesday or Wednesday. Not only do flight prices rise sharply for weekend departures and returns, but airports get more crowded. Skip the endless security queue and save a bit of money — about $86 — instead.Timing is also important when purchasing your tickets. For most European destinations, the old adage of "buy on a Tuesday" doesn't translate. Research has found that Sunday is the cheapest day to buy a flight to Europe, saving you a small (but not insignificant) $11. That's at least a few espressos!See: Best Family Vacations in EuropeParis, London, Rome... these are some of the most popular European cities for Americans to visit, but you can expect to pay for the privilege — they're also the most expensive to fly to. If you're not yet settled on a specific arrival country, consider Norway, Denmark, Sweden, Iceland or Ireland. Travelers departing from the East Coast hubs of New York, Boston and Washington, D.C. can find flights to cities in these countries for far less. For example, if you're flying from John F. Kennedy International Airport to Oslo Airport, you can expect to pay as little as $591 in August; Bostonians headed to Dublin can expect to pay around $809. By comparison, flights to Paris average $1,127; London, $1,047.If you have your heart set on eventually ending up in Paris, for example, fly into a cheaper hub, such as Keflavík International Airport. After spending a few days in Reykjavik, Iceland, you can take a more affordable connecting flight onto the City of Light.Flying across the Atlantic is likely your biggest expense when planning a trip to Europe, but don't overlook other savings you could nab. Instead of hotels, look into staying at vacation rentals. Sites like Airbnb and HomeAway both offer a slate of great properties around the world, and there's no better way to experience Europe like a local than by staying in an apartment. You'll likely spend less than you would at a hotel. Plus, you can shop for groceries in local markets, saving money on restaurant tabs.If you're hoping to hop between several European destinations during your trip, remember that the train may not always be the most affordable option. To ensure you're getting the best price, compare Eurail pass prices to cheap intra-European flights. If you're planning on moving about the continent, you can select and customize a Eurail pass to suit your itinerary. Single-country passes start at just $67 and multi-country passes start at just $120. However, you'll want to compare those prices to cheap intra-Europe flights on airlines like Ryanair and EasyJet; they're often more affordable.And don't forget to check out admission passes to popular tourist attractions. For example, the Paris Pass includes entry to 60-some museums and attractions, including the Louvre, Notre Dame and the Arc de Triomphe. Two-day adult passes start at 122 euros (about $133 — sizable savings if you're planning on hitting up multiple sights.)See: Best Places to Visit in Europe About the author: Dara Continenza is an editor at Hopper, the travel app that tells you when to fly and buy. She writes articles on air travel and offers expert advice backed by Hopper's unique data. Follow her for more tips and deals on Facebook, Twitter and Pinterest.