We can’t guarantee anything, but next time you sign up for a river lottery, take these steps to improve your chances at winning the trip of a lifetime. You know a river is popular when getting a chance to run it costs you both a financial deposit and a heartfelt prayer to Lady Luck. A handful of rivers and river sections in the continental United States require a lottery to commercially raft. Check out these tips for securing a spot on some of the most breathtaking.

The Colorado River, Grand Canyon National Park, Arizona

The Grand Canyon is home to perhaps the most notorious river lottery in the US. This one’s special in that it’s weighted, with more points awarded to those who haven’t been down the Colorado recently. To improve your chances, fill your boat with first timers, but make sure you nominate a trip leader and two potential alternate trip leaders that still have the river experience the NPS requires.

If one of one or more members of your group rafted in the last five years, consider splitting up the group such that all the recent rafters are under one application and all the relative newbies are on another; the lottery system will award an application the minimum number of points of anyone in a group, and you get a point for every consecutive year, up to five, you’ve gone without rafting through GCNP. The more points, the better.

If you’re dead-set on doing the river yourself, don’t go with a commercial service—that will reset your accumulated points. You’ll also have a better chance if you apply for winter dates (January, February, November or December). You’ll be more likely to encounter solitude on the water, but you should consider adding a dry suit to your packing list.

Entry Fee: $25

The Green River, Dinosaur National Monument, Colorado

The Green River flows from the granite spires and alpine meadows of Wyoming’s Wind River Range down through Utah and the rust-red furrows of Canyonlands National Park. The section winding through the steep-walled canyons of Dinosaur National Monument is one of the most popular, starting at the towering sandstone Gates of Lodore and rippling through a tumble of rapids called Hell’s Half Mile. You’re pretty much guaranteed a permit if you hit it during the off-season, but from the second weekend in May to the second weekend in September, you’ll need a winning ticket. Pick dates for later in the season (mid-August through mid-September) for better odds. Also sign up for the Yampa River, a tributary of the Green that also calls Dinosaur home, to double your chances for a trip.

Entry Fee: $15

Four Rivers, Salmon-Challis National Forest, Idaho and Oregon

The Salmon, Middle Fork of the Salmon, Selway and Snake Rivers all operate under the same Four Rivers lottery system. Of these, the Selway, home to some of the most challenging rapids in the US, is the most competitive; applicants have had less than a two percent chance of winning in recent years. Conversely, applicants have close to a 15 percent chance of winning a spot on the Snake, which carves the border between Oregon and Idaho and passes through Hells Canyon, the deepest gorge in North America. Early season applicants will have less competition than those vying for a spot June through mid-August, but for the best chance of winning, sign up for the last week of August onward, and be sure to check flows before you go.

Because there’s a single lottery for all four rivers, you’ll rank them by preference in your application. Stay open to giving your second or third choice a try. Committed to just one river? If you find cold weather refreshing, reserve a pre- or post-season launch date and avoid the lottery altogether. (Check the website for each river’s peak season dates).

Entry fee: $6

Rio Chama Wild and Scenic River, New Mexico

Steep walls of watercolor sandstone guard the class II rapids of New Mexico’s Rio Chama, offering scenic floats as well as good rainbow and brown trout fishing in the far upper reaches. The 31-mile section typically take two or three days to navigate. If your day job offers flex hours, this is the river for you: Lotteries only operate on weekends from May 1 through Labor Day weekend, so if you can play hooky for a few days, the river’s all yours. (Call in advance to make a reservation). There’s a catch, though; You can’t run the Rio Chama in a raft 12 feet or shorter if the flow is less than 300 cubic feet per second, and the El Vado dam often releases extra water on the weekends only. For the best chance of a successful mid-week run, check flows first or plan to go during June when the current is generally swift and consistent. Can’t get time off? Request three separate dates on your application for a better chance of winning a coveted weekend permit.

Entry fee: $6

Smith River, Smith River State Park, Montana

Besides the regular lottery, this 59-mile, scenic, trout-rich section of the Smith River has a “Super Permit” lottery. That’s the real jackpot; winners of the Super Lottery can launch on any one date of their choosing over the course of peak season, May 15 to July 15, when the water’s high. However, things can get expensive in a hurry; it’s a raffle ticket-style system, and the more $5 chances you purchase, the better your odds of winning.

Make sure you file your application for either lottery under the name of someone who hasn’t rafted in the last year, or the application will be thrown out. Recent rafters can, however, join an existing float trip with impunity.

Entry fee: $10

Salt River, Salt River Canyon Wilderness, Arizona

Sometimes called “Arizona’s Other Grand Canyon,” the Salt River Canyon owes its rugged cliffs to the time-worn journey of the Salt River. The canyon drops 2,000 feet over its length, and rafting the Upper Salt will have you tackling class III and IV rapids—not for the inexperienced or faint of heart.

Lotto-allotted permit dates run from March 1 to May 15 every year. On average, you’ll have a 20 percent chance of winning, but you can dramatically boost your odds by giving local spring break week and the Easter holiday a wide berth. The calendar remains pretty open late season, but that’s for a reason: usually the Salt is dried up by May if not late April. Even so, putting down a mid to late April launch date as a third choice on your application will increase your odds of getting chosen. Just hope there’s water.

Entry fee: $16

Rogue National Wild and Scenic River, Oregon

The Rogue has its birthplace in one of the greatest places to snag the sunrise on the Pacific crest: Crater Lake National Park. From there it drifts through green valleys and picks up speed through Mule Creek Canyon and the Blossom Bar Rapids, coursing toward the Pacific Ocean. The 33.8-mile section of river designated as Wild and Scenic has a lottery from May 15 through October 15. Fortunately, there’s a way around it for those who aren’t picky about launch date: Check for Float Space Openings on the BLM web page during the first five business days of April to snap up remaining spots. Walk-in reservations are also available sporadically throughout the year. Show up at the Smullin Visitor Center with your gear in tow on the day of launch and ask if any permits have opened up.

Entry fee: $6