switching up growing method.

Hey folks!
Its been a while since I've posted anything as I've been in the process of moving house.
Needing some advice:

When i was moving my cacti i lost quiet a few to rot that was not visible where they were, the side that rotted was the side facing the sun,  i never get the bodies wet except when using pest control and the rot was very advanced (only treated for pests recently)
So in light of that my intention is to be a lot harder with my watering regime my only concern is root loss. .
Any ideas how to manage this?

Also the new place has no undercover area so i have converted the brightest spare room into a cacti room just have to keep an eye out for stretching and move those guys to the windowsill fingers crossed they get through the next year. .