Sparks31 put up a couple of posts on running a monitoring exercise (MONEX) designed to use basic radio receiving equipment, get you experienced in listening, test your gear, and give you an idea of who is operating in your area and their frequencies. The first exercise in part 1 uses a portable broadcast FM radio and the second an AM radio, which just about everyone has. These are exercises that you can do on your own and only require the ability to receive. You do not need a license to receive radio communications.
MONEXes (Monitoring Exercises) are important because they help you understand what your listening equipment is capable of doing, they help you improve your skills in both COMINT and OSINT, and they help you figure out what frequencies in your area are useful for keeping an ear on events. Communications monitoring equipment is not something you can purchase and toss in a go-box for when the balloon goes up. You need to get proficient with the equipment before the s[tuff] hits the fan. Information gathering is as important a survival skill as firearms proficiency, or growing your own food. MONEXes are the way to COMINT proficiency.
Consolidated Frequency List (pdf) This contains a long list of to whom various frequencies have been allocated for use. (H/t Sparks31)