Keep it clean
A "popped blister" is similar to an abrasion & is not a deep inury usuallly.
You mainly want to prevent complications such as infection while it heals. Gentle cleansing & keeping it moist with an ointment every day will help it heal without scarring
. If it is in an area that is rubbed by clothing, keep it covered with a bandage to prevent further traumatization of the area until it is healed.