First, you need to know that there are 2 different terminals:
- LCCT (Low Cost Carrier Terminal), which is specifically for passengers using the Air Asia flights; and
- KLIA, which is for all other airlines
Picture of a pre-purchased bus ticket. You can board the bus, and wait for the staff to go for his ticket rounds. At this time, you can either buy your ticket or show them your printed online receipt. You'll get a bus ticket like the one above, which you will have to return one portion upon leaving the bus.
If you land at KLIA, you can take the train instead. Look for the sign KLIA Ekspress (in pink), and take the elevator down from the arrival terminal.
Porters will be there to help you with you luggage (no tips in Malaysia). The train ride is about 30 minutes from the airport to the city. Then, from KL Sentral, you can board a taxi or take the city train to get to your destination. The ticket can be purchased inside the airport, near the luggage conveyor belt area. It costs RM35 one way, and the train arrives every 15 minutes.
Here are additional links that might be helpful during your traveling.
The first link is a new service provided by KLIA Ekspres to LCCT. The cost is RM12.50 including the train and bus fare to LCCT. Click on the tabs to check their schedule. The bus and train arrives every 30 minutes. Not sure how long is the ride though. Anyone can comment on that?
This second link provides information on the airport bus services from one terminal to another, KLIA-LCCT.
Airport bus service