Hi all happy Memorial day,

I want to install a window a/c unit. I have been doing some how to reading up on it. Some sites say make sure to fasten the a/c unit to the brackets or directly to the aluminum/wood part of window,and make sure the a/c unit is level. Others say make sure the a/c unit is at least a half bubble off level (leaning towards the outside) so it drains properly and does not collect to much moisture in the unit.
Others say window a/c units are designed to operate with at least a 1/2" of moisture water in the collection tray at the bottom of unit. Does anybody know what is right? Off level,on level,fasten screws directly through the units cabinet into the window at certain points? I know some install procedures varie between a/c unit brands,but i thought for the most part they were similar..?

Thanks to all responders!