Don't. It just contributes to chaotic boarding. About 12 months ago on the DXB-CGK route, boarding was continually like joining a rugby scrum as many passengers surged forward blocking all access to the bridge. First and Business passengers literally had to push through the mass to get on - if I had been paying those ticket amounts I wouldn't have been impressed. The boarding on that route each way, seems to be improving as the gate staff are managing it better and being strict with passengers telling people to wait until their zone is called before boarding.

But I empathise re: getting a spot for your hand luggage near to where you actually sit.