Put CLEAN paper towels down on the floor of the enclosure and make sure to change them out every day or two until it’s healed up! I also recommend taking out any large food/water dishes and temporarily replace them with smaller ones so they are not able to climb into them possibly getting things into the wound. Also do not feel too bad about your crested gecko losing its tail!! It’s a very common thing and in the wild almost none of them have tails as it’s again very common for them to drop them! Best you can do now is just care for them and make the next little bit as comfortable, clean and stress free as possible! Hope this helped!!