If you're travelling internationally to an Asian country, take Air Asia It's really cheap, it's a budget airline but you have to pay for like food, blankets etc ahaha so yeah! But it's worth it if you're just worried about how to get there and you don't care about the service/facilities!
I use hotwire for flights and car rentals, and booking.com for hotels. Pretty good deals there. If I'm going to a city with good public transportation then I'll use that instead of renting a car. And traveling during the week is cheaper than traveling during the weekend.