You may want to just shave the cheeks the first few times till you get used to it.
Sometimes trying a full shave when new will just end less than ideal. If you feel brave, go for it.
Cheeks first, pulling skin tight the opposite direction to moving blade and finding the proper angle for comfort and build on that as you venture further around your face.
Good WET lather - almost dripping, is ideal for straights.

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