The best way to dry down is in a tumble dryer. Always check the care label of your jacket for guidance on heat settings.
Regularly check your jacket by removing it from the dryer, shaking it out and pulling the clusters apart every 20 – 30 minutes. Ensure it is totally dry to avoid any clumps, then air out for a few days.
An easy mistake to make is tumble drying your down jacket for until the outer fabric is dry, assuming that the down clusters inside are also dry. When down gets wet, the clusters collapse and form clumps. If left damp, down jackets can be rendered useless and need to be replaced.
Store your jacket uncompressed and do your very best to keep it dry; try to avoid using down in damp environments.