Manipulate tension to trigger new gains. Remember, hypertrophy is stimulated mostly by muscular tension. Muscles get the most tension where the resistance curve is at its peak in the concentric (lifting) point of a movement.
For dips, anchor a band with a heavy dumbbell at your feet. Placing the band around your neck looks awkward, but it will naturally bend you forward and cause the pecs to get into a deep stretch. This will also create more tension at the top of the rep.
A perfect warm-up virtually ensures a perfect workout, but a poor one will almost certainly ruin what COULD have been a great training experience. Ever wake up dreading the idea of going to the gym, but after getting there, you end up having a great workout? You can thank your warm-up for that.