Recon sometimes is just walking and observing. If you know what to look for you can notice things that are in the wrong place. Vulnerable spots and ways in.
Another good thing to have is a small laptop or an iPad. Run a stumbler or signal scanner, stash the laptop or iPad on your pack and just walk. If you find one, mark the spot and return. Try to capture packets and see if you can crack that wireless or bluetooth.
Have a little notebook - I prefer Field Notes or Rite in the Rain - and sketch a quick map of the area and take notes of what you see. Jot down atmospherics: people’s behavior, cars, cameras, points of interest, etc.
Do this a few times and if the atmospherics remain the same you know you have the place down and you can start planning.
Remember: On a day-to-day basis, security is mostly about paying attention.