There are just about as many ways to get there as there are guests who visit. But don't assume that it's your only option. Long Beach Airport is also closer, but isn't served by many carriers. At the airport there are shuttle busses which will take you to the hotels in the Disneyland area. Prices are competitive, depending on the season, and you can compare prices between the different shuttles before you pick one.
Taxis are also available but much more expensive.
The best way to drive to Disneyland changes from day to day or hour by hour depending on freeway traffic conditions. Caltrans, the State of California Department of Transportation, offers a way to search for Current Road Conditions that can tell you about construction and other delays. The City of Anaheim offers a Progress Report on area roads and construction. Disneyland's official site offers Driving directions along with maps of the park and general area. Before you go anywhere after you park, write down your lot name, section, and row number if you ever want to see your car again.