Pick one weight and leave it there for the whole session. The overhead press is the weakest link, so set the dumbbells by that.
Test it: press them overhead 10 times. If reps 8, 9 and 10 are hard but your form still looks the same as rep 1, that is your weight.
A common first-session starting point is 4 to 8 kg (10 to 18 lb) per hand, but the 10-rep test beats the number.
Squats and rows will feel easy at that weight, and that is on purpose. If something feels too light, take 3 seconds to lower it rather than changing the dumbbells.
Nothing on the floorEvery exercise is standing, on the bench, or on the machine.Breathe out on the effortPush or pull on the out-breath, and do not hold your breath.Two movements, one repIn the paired lifts the second movement starts as the first one finishes. It is one flowing rep, not two exercises stacked.Stop means stopSharp pain, dizziness, or a back that rounds under load: put the weights down and move on.