Thinking about going on a camping trip this summer? If you want a premier site in the peak season at one of Maine’s most popular campgrounds, it’s probably too late.

Securing the state’s most coveted campsites requires planning ahead, persistence and flexibility. At certain campgrounds, the reservation process is highly competitive, with people hopping online or on the phone as soon as the sites are available to book. So, whether it’s for this year or next, start by familiarizing yourself with how the process works at whatever campgrounds you’re interested in and marking the dates and times that reservations open on your calendar.

Before they do, study the campground map and pick out the sites you like, along with several backups. And know your priorities — whether it’s the site itself or dates or days of the week of your stay. The more flexible you can be about the other aspects, the closer you’ll come to having your ideal camping experience.

Here’s some key info for a handful of popular Maine campgrounds:

BAXTER STATE PARK, Millinocket

Sites: 337, most popular are the bunkhouse and lean-tos at Chimney Pond and cabins at Kidney and Daicey Ponds, as well as campgrounds near trailheads (Roaring Brook, Katahdin Stream and Abol)

Rates: From $15 for a bunk to $185 for a six-person cabin per night; $38 for campground tent site

Reservations: Open Jan. 15 on a rolling basis, four months ahead of the booking date. Most can be made online at baxterstatepark.org except for anything in the month of May, backcountry and group sites, bunkhouses and Chimney Pond and Russell Pond, which must be made by phone, mail or in person.

To book a multi-day stay, reserve the first day online when the site opens at midnight, then call the reservation office (207-723-5140) following business day at 8 a.m. (so more than 24 hours later) to extend your stay.

CUTLER COAST PUBLIC LAND, Cutler

Sites: Five primitive, hike-in campsites

Rates: Free

Reservations: None. Check log-in book at trailhead for openings and sign up.

DUCK HARBOR CAMPGROUND, Isle au Haut

Sites: Five lean-to shelters

Rates: $20 per night (three-night maximum)

Reservations: Open at 10 a.m. April 1 at recreation.gov for season (May 14 to Oct. 5). Sites book up in minutes.

HERMIT ISLAND CAMPGROUND, Phippsburg

Sites: 271, plus three cabins and a yurt, with photos and descriptions at hermitisland.com

Rates: $54-$79 in-season (June 27 to Sept. 21), $49-$59 off-season (May 23 to June 26 and Sept. 21 to Oct. 13); see website for cabin/yurt rates

Reservations: To book a week stay or longer or for three days on Memorial Day or Labor Day weekends, send a letter with your reservation request and a check for a $125 deposit before Jan. 1. For shorter stays, the phones open on the first business day after March 1. Call 207-443-2101 from 9 a.m. to 2 p.m. Monday through Friday. As of mid-March, the campground was about 70% booked for the regular season.

MAINE STATE PARKS, statewide

Sites: Various among 12 campgrounds, though two (Aroostook and Cobscook) are under construction and not currently taking reservations

Rates: $15-$35 per night for Maine residents; $25-$45 for non-residents

Reservations: Opened Feb. 3 for Lily Bay and Sebago, Feb. 6 for rest. Make online at maine.gov or at the Reservations Call Center at 207-624-9950. Some walk-up sites available. Lily Bay and Rangeley Lake were most full as of mid-March.