Naming a guardian in your will is only the first step toward making sure your children are cared for if something should happen to you. Your will isn't a court order – it's just a document that makes your wishes known. You can take certain actions to help ensure the court honors your request.
Selecting the Guardian
Selecting a guardian can be a torturous task because so many considerations are involved. If you name your parents, it's possible they could predecease you, or they could be too old to feel up to the job. If you're divorced, custody likely could go to your ex as their sole living parent, no matter what your will says. Speak with the individual you're nominating as guardian to make sure he's willing to raise your children. Consider naming someone else to handle the children's inheritances, so one individual doesn't have unilateral control over your kids' welfare and finances.
Getting Court Approval
The court will likely approve your selection for guardian after your death. As a practical matter, courts almost always do so, unless the person you nominate is unfit. You can avoid a problem after your death by writing down why you chose the person you did, particularly if you don't want custody to go to your ex. You can explain to the court why you don't want the children's other parent to raise them, and if your reasons are compelling enough, the court might agree. Make sure your named executor has a copy of your written explanation, or attach it to your will.