When it comes to custody cases, parents may choose to file a parenting plan (a proposed custody and/or visitation schedule) with the court. If parents do not submit a parenting plan, the court will decide on a custody arrangement for the parties. As with most other states, Texas courts may consider the child's own wishes when making a custody determination. 

In addition, the court also considers a number of other factors, including: 

Whether joint conservatorship (joint custody) would benefit the child's physical, psychological, and emotional well-being; 

Whether each parent will encourage and promote a relationship between the child and the other parent; Whether the parents can communicate effectively to make decisions that promote the child's best interests; How much each of the parents contributed to the child's upbringing before the custody case was filed; How close or far each parent's home is located in relation to the other; and

Any other factors the court determines should be considered under the circumstances of the case. 

Information courtesy of site below.

See more at: http://statelaws.findlaw.com/texas-law/texas-child-custody-laws.html#sthash.963bBEwP.dpuf