One of the most important parts of your will is the appointment of your Personal Representative (aka PR). This is the person who will make sure that your wishes in your will are followed, and will settle all of your final bills and make distributions from your estate to your heirs.
So how do you pick someone?
First, resist the temptation to name more than one person. While some of my clients don't want to pick between their kids or siblings, this is a job best done by one person. It saves time and energy to only require one signature, where as joint PRs may have to both sign.
Second, this person will need to stay on top of deadlines and keep detailed records. He or she will talk to banks, insurance companies, realtors, and more. I recommend choosing someone who is good with details and known for being fair.
Third, I always recommend picking someone who will be aligned with your wishes. This could either be someone who stands to inherit from your estate, or someone who would support the person who will inherit (for example, your child's grandparent or favorite aunt). The Personal Representative is entitled to reasonable compensation for their work on your estate. However, if he or she draws a salary from your estate, then he or she will pay income taxes on that money. If he or she stands to inherit money from the estate (or supports that all of it is going to your kids), then he or she may opt not to be paid since the taxes on inheritance will be less (possibly even nothing).
Lastly, always, always, always name back-up personal representatives. Most of my clients name their spouse as their first-choice personal representative, which makes the most sense as spouses have an unlimited exemption to inherit free from estate taxes and are likely to be the person most invested in carrying out your wishes. However, your spouse may not be able to serve for whatever reason. I recommend including a second and third choice, and then allowing for a professional fiduciary to serve just in case.