Try to visit during the day, in the middle of the week. Montmartre is one of the most popular tourist destinations in Paris and tends to be packed on weekends most of the year and even during the week in summer months. Try to go during an off time, such as early morning on a business day, to avoid crowds and get better photographs of the view.
Reserve at least half of a day. Montmartre is set high on a hill overlooking the city of Paris, and it will take you some time to get up and get back down. If you are staying in the 18th arrondissement, this step does not apply to you, but for tourists staying in popular neighborhoods such as the Latin Quarter and Le Marais, the trip to Montmartre will take the better part of a morning or afternoon.
Take the metro to Abbesses, Anvers or Pigalle. Montmartre does not technically have its own metro station and is located in what can be called a sort of transportation "black hole." You will only be able to take public transportation such as the metro and bus system to the areas that surround Montmartre, which include the neighborhoods of the 18th arrondissement.
Use the Little White Train or the Montmartrobus. The RATP, Paris' public transit system, provides a bus that will take you to the top of the Butte Montmartre while touring the charming, historic neighborhoods along the way. Another option for trekking up the hill is the Little White Train, which picks up tourists at the Place Pigalle and takes them on an informative tour up the hill.
Go to the Sacré-Coeur before heading into the winding cobblestone streets of the old village. The Basilique du Sacré Coeur is home to an impressive mosaic ceiling and the 18,835 kilogram "Savoyarde," which is the largest church bell in all of France. Entrance into the Sacré Coeur is free, but it is customary to leave a small donation.