If you ask for a rehoming fee, do not ask for an unreasonable one, often times under $100 is sufficient to make sure the person interested is prepared and ready to take on the animal.
Take great photos. Pictures are the first thing people see. You want them to grab attention and make people interested.
Check the post often or set your facebook to give notifications. Being responsive will help the process move faster.
Keep an open mind and be realistic. Although it may not be the perfect home you imagine for your pet, a home is always better than a shelter if the home seems fit enough to provide love, food, shelter, and water.
Be honest about the needs of the animal. If the animal needs medical care, training, or a household without kids or other animals etc. kindly let the new family know. Phrases such as, “would do well in a home with older children”, or “prefers to be the king/queen of their castle” are ways to articulate certain behavior needs.