When the weather started to heat up last year, I wrote a post on what you need to know when choosing between a window air conditioner and hooking up to central air. That post has continued to have a high click-through rate, because I guess everyone is curious about their cooling options–especially when they’re on a budget.

One of the most interesting takeaway messages from this post was this: if you own a small home or don’t need to have your entire home cooled at once, you may be better off with one or two window air conditioners rather than upgrading to a central air system. The only caveat to this advice was if you lived in a high-humidity locale. Then the window a/c units probably can’t provide the cooling you desire.

Consumer Reports just came out with its listing of the best deals in air conditioning, including energy-efficient options that might earn you a tax credit. Here are CRs four tips on what you need to know to keep cool this summer:

1. Getting the wrong size is the most common mistake people make, regardless of the type of cooling system. Purchasing a unit with too small a capacity could lead to inadequate cooling, while a unit that’s too large could lead to a cold, damp space.
2. Upgrading your existing central air, don’t automatically buy the same-sized system. Changes that have improved energy efficiency, including new windows or added insulation can reduce cooling needs, while added rooms could increase needs. Contractors should do a load calculation as well as evaluate if ducts need to be resized, sealed and insulated, or replaced.
3. Adding central air may make the most sense if the home already has ductwork for heating.
4. Consider replacing window units made before late 2000. Energy Star-qualified window models use about 25 percent less electricity than models even from just nine years ago. Unsure what size unit to get? Use the room-size guide on the A/C page at the Energy Star website to find out.

How are you planning to stay cool this summer?