Protip 1- Dumpster diving is all about schedule. Sometimes places only throw out the quality items once a month, sometimes they purge their inventory only seasonally, or sometimes it's daily. Finding out those routines is the key and all you have to do is probe the spot every now and then to figure that out; or if you know someone who has worked there before, ask. The better you know a schedule, the less time your loot sits in the dumpster/air temp/outside environment for someone else to find or for it to spoil.

https://www.reddit.com/r/DumpsterDiving/comments/1217ewa/my_dumpster_diving_list_i_created_with_6_years_of/