If interested there is an old thread on this topic found here: https://www.seriousgmod.com/threads/map-secrets.16338/ I don't think it's updated for most of the new maps, but there is a fair amount of information about older maps and semi-newer maps in the comments of the thread.
Haven't seen anyone bring this up here, but the first button on 67thway is glitched so that you don't have to press it. The second button automatically spawns and you can just start from there. Also, you might want to find/add the Highrise secret knife. I know that the last step is throwing the turtle found on the highest crane off of the map and then going into the helicopter, but idk the steps before then.
Can't sell map secrets if I'm going to reveal them all give me 15k points or I will spoil every map secret so no profit 4 u