=Getting Started with Planefagging==
ADS-B Exchange - learn how to use the filters
Radarbox - flight scanning
Flightaware - very useful for flight histories and arrivals lists
Flightradar24 - flight scanning
You also need to be able to spot unusual patterns, things that 'don't look right' against the backdrop. It's a skill you can develop and eventually you develop a 'usual suspects list' that KAF R1 has that we watch.
German Air Force, swiss Air Force and French Air Farce aren't to be trusted. 2-reg planes are 'wheelmen' for the wealthy, such as Spros as they can't travel via normal routes. 2-reg planes are 'military' and can bypass some customs checks (hint).
ATC Live can be useful if you know a happening is going on around an airport. Listening to the Tower can provide insight.
Anything else, just ask. Kekistan Recon 1 can always use new recruits.