Guys you gotta use the mechanics.
1) Send people with the right tools to SCOUT the place first, so you know how many doors and windows and zombies are there, you don't need to send weapons just binoculars and flashlights.
2) BEFORE even dreaming into breaching inside a place you gotta first ASSAULT IT, if you have crossbows or silenced weapons you can shoot the zombies INSIDE the building which means thinning them down
3) Then you breach, you breach when you have assaulted the place at least 3 to 4 times, use weapons with ASSAULT stats for ASSAULTS but for BREACHS go for a combo of MELEE and SILENCED RANGED
4) It takes times with the worst survivors, if you got 3 you put ALL of them outside (once the breach hsa been succesful and if you don't need to retreat) you put them all outside smashing zombies, when the diary reports that you've been smashing fewer and fewer you can trust your best guard to do it and send the others to BARRICADE or BUILD TRAPS (that's your strategy) or of course... SEARCH/LOOT and leave.
The game becomes easier once you understand you gotta take things step by step instead of going full retard.
