I followed some of the advices that I had online, I strained my cuffs. Eventhough I followed the form strictly, I do not feel pec involvement at all. I then switched to dumbbells and I got it right. What I learned is that, every body works differently. One can be right on something but it doesn't mean that it's also true for you.

Well yeah, I've read about benchpressing forms. Most of them typically says pinch your scapula together, have a slight arch on your back, foot planted firmly on the floor. Your wrist and elbow should form a straight line while holding the bar, slowly lowering the bar to your chest on your nipples. Breathe in before lowering the bar, breathe out while pressing upwards. I followed this yet I got most of the load on my shoulder.

I did further reading about the cause of this and came to the conclusion that my pecs are stronger than my delts and arms so I don't feel fatigue on my pecs. I've been doing this for a few months and decided to switch to something else.

I started out with 10kg dumbbells then progressed to 24kgs for 4 reps without any assistance. I felt most of the contraction when I go heavy. My pecs struggling to bring my arms together and I felt my pecs pinching together on the final upwards movement. I then drop the weight to 20kgs on my next sets to do at least 6-8 reps. I now have less soreness on my front delt and more on my pecs.

So you're right about trial and error. Every body works differently. Mine responds better with dumbbells.

It's mostly trial and error on that part. Flexibility comes in to play, I'm not very flexible. I slowly turn my palms facing inwards while lowering the dumbbells then return to the normal bench pressing grip on the way up. This way I feel less stress on my front delts.