If you start out by doing flat dumbbell presses the amount of weight you can use when you get to 90 degrees will be severely limited. (fitnessdoctrine.com)
Day 1 - Chest, Back, and Arms 75 Degree Incline Press Flat Dumbbell Press Incline Flyes One Arm Rows Two Arm Rows Pullovers Dumbell Curl Incline Curls Overhead Triceps Extensions Lying Tri Ext (hugorivera.net)
To be safe, do shoulder - friendly variations wherever possible (e.g. replace barbell shoulder press with high incline neutral grip dumbbell press; replace bench press with neutral grip flat dumbbell press). (kingofthegym.com)