Short answer — use a price-comparison tool first (Google Flights, Skyscanner, KAYAK/Momondo), then confirm and buy on the airline’s site (AirAsia, SriLankan, Malaysia Airlines) or a large, trusted OTA (Expedia / Trip.com) if the OTA price/conditions are better.

How to get the best deal (quick steps)

• Search broadly and compare: use Google Flights to see date-flexible calendars and to start price-tracking, then cross-check results on Skyscanner and KAYAK (they often show slightly different OTAs/promotions). (google.com)
• Watch the low-cost carrier first: AirAsia frequently has the cheapest nonstop fares CMB–KUL — good for bargain fares but expect add‑ons (bags, seat selection). Check AirAsia’s site/app for final prices and baggage rules. (info.flightmapper.net)
• Compare full‑service carriers too: SriLankan and Malaysia Airlines operate direct flights and include more in the base fare (meals / larger free baggage on many fares). If you value included baggage or easier changes, those can be better value. (flightsfrom.com)
• Set fare alerts & be flexible: use the “whole month” or calendar views and set alerts on Google Flights, Skyscanner or KAYAK — moving dates by a few days or flying in October/other low months often cuts the price. (google.com)
• Book direct for service reasons (after you find the best fare): once you’ve found the fare you want, consider booking on the airline’s website to make changes/resolve disruptions easier — U.S. DOT and travel experts note airlines will have more direct control/support for tickets they sell. If an OTA offers a materially better deal or useful protections (price‑drop protection), a large OTA (Expedia, Trip.com, KAYAK) is also a reasonable option. (transportation.gov)

Quick site checklist (start here)

• Google Flights — fast calendar, price-tracking and “explore” features. (google.com)
• Skyscanner — whole‑month view and cheap‑month suggestions. (skyscanner.com)
• KAYAK — recent-deals view, price predictions and alerts. (kayak.com)
• Airline sites — AirAsia (cheapest on many dates), SriLankan, Malaysia Airlines — confirm final price/baggage. (info.flightmapper.net)
• Large OTAs if you prefer packaged deals or price protection — Expedia / Trip.com / Travelocity. (expedia.com)

Two practical tips

• Low‑cost carriers like AirAsia often advertise very low base fares but charge for baggage/seat/priority. If you need checked luggage or seat selection, add those fees when comparing total cost. (newsroom.airasia.com)
• If you want the best combination of price + flexibility, find the fare on an aggregator, then compare the final price and change/cancellation policy on the airline site before you buy. The U.S. DOT recommends contacting the seller (airline or agency) that issued the ticket if problems arise. (google.com)

If you want, I can:

• run quick, live searches for your exact travel dates and show cheapest options (AirAsia vs SriLankan vs Malaysia Airlines vs OTAs), or
• set up a comparison of total trip cost including 1 checked bag and seat selection for specific dates.

Which would you prefer?