Best way to have velocity in freestyle

Hey all. I’ve recently signup for lifeguard, so i need to pass on some swimming exams. The thing is, i’ve been swimming for some years, but each teacher has their own opinion about how to propel better with the hands.

First i was taught that the hand at the front should start moving outwards and downwards, then upwards and inwards then straight back parallel to my body and velocity. They said we shouldn’t proppel the water straight all the way from the front position to back because it wouldn’t give the same propulsion.

Then last month this new teacher, told me that’s an old fashioned way, and that the way to do it is always straight, firstly downwards, on the middle upwards and then parallel.

He also said i should keep my head in the direction i was going like if i was trying to look to the ceiling, instead of having the head relaxed, looking to the bottom of the swimming pool. I’ve been thinking why that might be, but i can’t find a reason.

So i was hoping you guys could shed some light on this, so i don’t have to change technique everytime i meet a new teacher.