With school letting out and sultry summer days ahead, it's time to start thinking vacation.

Because it's a supply-and-demand world, you'll likely be up against higher airfare, hotel costs and car rental rates. But here are some tips to help keep things affordable.

If by air …

If you plan to fly domestically, your best chance to score cheaper fares is by booking about 60 days in advance. For international travel, make it 90 days. This may also be the right time to cash in frequent-flier miles or companion fare coupons. Comparison websites such as Kayak, Skiplagged and Airfarewatchdog can turn up cheap airfare.

If by land …

Make sure your vehicle is in good running condition. The last thing you want is a blown engine in a one-mechanic town. Depending on your route and time constraints, Amtrak or Greyhound may be affordable alternatives. Renting an RV may also pencil out, particularly with relatively low fuel prices.

Consider visiting places during their off-seasons

After major league baseball teams break spring training camps in Arizona and Florida at the end of March and it really starts to heat up, airfare and room rates tend to drop dramatically beginning in mid-April and lasting through the summer. You can find high-end hotels with luxurious swimming pools to keep the kids happy for hours. Just remember to get in your golf, tennis and hikes before midday.

Accommodations

This can be a touchy subject because comfort levels are highly personal. If you're traveling solo to a metro area and don't mind roughing it, check out Couchsurfing. Priceline claims to save up to 60% over published hotel prices. You won't learn where you're staying until your bid is accepted, but you name the price, and you can make another offer if your initial one is rejected.

Home-swapping companies operate domestically and internationally. Most often you arrange to exchange homes simultaneously, but in some cases you can stagger swaps to accommodate travel dates. There are fees to join home-exchange services, but typically they are more than offset by savings from avoided hotel costs. Sites to check include Love Home Swap, Knok, HomeLink, HomeExchange and Intervac. You may also be able to exchange vehicles.

The great outdoors

Circling back to the RV idea, or for those otherwise open to camping, there are nearly 500 KOA campground sites in the U.S. and Canada. State and national parks are extremely popular in the summer, so campgrounds can fill up fast. Make reservations as soon as you can. For $80 you can pick up an annual pass valid at national parks and federal recreation lands for a full year from the month of purchase. It covers the pass owner and three accompanying teens and adults age 16 and older. No entry fee is charged for children 15 and younger.

And if you really want to save …

Consider daytrips to places you've been meaning to visit near home. Hikes, wineries, picnicking and swimming at nearby lakes, fun cycling routes, water-park rides and music festivals may fit the bill.

Also, when inquiring about rooms or car rentals, it doesn't hurt to ask whether they offer discounts for seniors, AAA or other memberships. And sometimes you can save money through credit card partnerships with hotel chains or car rental companies.

Peter Lewis, NerdWallet © Copyright 2016 NerdWallet, Inc. All Rights Reserved