1. Make your plan. : Where to go? How to get there? What kind of accommodation will stay? How many places to go?
2. Some ticket needs to buy in advance. : Some show or some places you need to go need a ticket to get in. It may waste your time if tickets were run out and you can not get one. So, check first and don't forget to check a schedule.
3. Set your own package. : For example: roundtrip air travel, 2 nights accommodation, 2 days rental car. Better buy in package than each of them separately and you will get cheaper price from agency.
4. Go with others. It will make your travel cheaper if you got someone to share some expense with you. Ask members of your house, friends or neighborhood if they want to join your trip, the more the better you will have more power to ask for a bargain from agency, also you can share rental car and fuel with them.
5. Compare price from at least 3 agencies. The more the better and don't forget to compare quality and services as well.
Finally, don't forget that travel in high-season, you will be charged more. If possible try to avoid travel in high-season period.