After returning from a relaxing 12-day trip to Hawaii, I unpacked my suitcase and sorted through vacation photos. You know what I didn't do? Nervously wait for the credit card bills to arrive. Using reward points and some creative thinking, we spent less than $2,500 on our trip for four to Kauai and Oahu. Throughout the year, we charge most of our purchases to a rewards credit card and then pay it off every month to avoid interest. We are also lucky enough that my husband's company lets him keep the frequent-flier miles he earns on monthly business trips. Over the years, we have put together budget trips to exotic locations including Alaska and Costa Rica.

Here are six tips we have learned along the way:

1. Be flexible

When we began researching the trip, we were willing to travel anytime during my children's three-week fall break from school. We were also open to visiting any of the Hawaiian islands, though Kauai was my preference. Our flexibility, along with traveling off-season, helped us snag tickets at the lowest reward level.

"Airlines have different tiers of rewards available. If you are dead set on a certain day, you may spend more miles on the ticket than if you were willing to leave a day earlier or have an extra layover," says Matthew Klint, Live and Let's Fly blogger and founder of Upgrd.com. "You can save hundreds of thousands of miles on tickets for a family if you are a little flexible."

2. Consider alternate airports

At this point in the planning process, we had enough miles to fly to Kauai but not enough to cover round-trip tickets. Luckily, we soon found a flight home out of Honolulu and were happy to discover cheap inter-island flight options from Kauai to Oahu. John Ulzheimer, CreditSesame.com president of consumer education, says to look into flying in and out of nearby airports which may have more frequent-flier availability -- Midway instead of O'Hare, for example, or Fort Lauderdale instead of Miami. When looking at the alternatives, don't forget to factor in extra costs -- gas, parking and time -- in order to ensure sure your plan makes financial sense.

3. Pick up the phone

When my husband couldn't find available frequent-flier tickets for our destination online, he called our airline and an agent found four tickets available during our school break. Unfortunately, the route involved five different airports, which wouldn't exactly be a good time with two kids in tow. My husband had the agent hold the tickets, hung up the phone, and called the airline right back. This time a different agent found us tickets that required only one layover. Klint says my husband did exactly the right thing to find tickets.

"Airline websites don't always have all of the available seats listed. Call an agent and if they don't seem to be knowledgeable, call back," says Klint. "This is especially true if you are booking a rewards flight through a partner airline, which isn't always on the website."

4. Check available points on all your cards

Since we were going through Oahu to maximize frequent-flier miles on our way home, we decided to stay overnight and visit Pearl Harbor. We checked on one of our little-used credit cards and realized that our rewards points had really added up over the years. Instead of paying out of pocket for a room, we redeemed our points and stayed at a boutique hotel where we could see the sunrise over Waikiki from our bed. If you don't have enough points for a hotel or car, Ulzheimer recommends redeeming points for a gift card that you can use on your trip to cover items like food or gas.

5. Be creative with lodging

Since we didn't have enough rewards points to pay for 12 nights of lodging, we asked my husband's parents to let us trade their time share as our Christmas present. Instead of paying thousands for a hotel room overlooking the ocean, we only had to pay a $200 trade fee. While you might not have a relative with a time share, you may have a friend with a beach house or a client who might be willing to give you a reduced rate on their mountain cottage.

6. Use best rewards cards for trip purchases

When I pulled out my credit card to pay for our boat ride down the Na Pali Coast, I made sure to use the card that offers the highest rewards points, effectively kick-starting plans for a future getaway to Belize while still soaking up the sun in Hawaii.

"Some cards give up to 5 percent cash back on travel expenses, which can be a great jumping off point for your next trip," Ulzheimer says.