Looser hook first.
Hook your bra on a looser hook first. Move to the tighter hooks as your band stretches out over time.
Scoop and swoop.
Gather breast tissue from the side/underarm area then gently lift each breast so that all the breast tissue sits inside the cup and is properly supported.
Adjust your straps.
Straps tend to loosen so make sure to adjust to the appropriate length every now and then to avoid slipping straps. Rule of thumb is to be able to stack two fingers between strap and shoulder.