My main tip for avoiding leaks is to put a 'shower cap' on the car. I've used normal sheets, plastic wrap etc.
The main areas water comes into mine (original roof with ash bar at front) is around the point where the windows meet the roof and the rubber trim at the front by the a pillar.
covering this aea with a sheet is pretty effective. Certainly saved any wet inside whilst parked out in frankly tropical storm conditions in the south of france last summer..
On the move, I just ignore the odd drip, though I'm sure that maybe re-waterproofing the hood might help water roll off rather than soak through perhaps?
