Can I nominate a guardian and conservator for myself?
Yes, you can. This is generally done as part of a durable general power of attorney (POA). Like a will, a durable POA has been signed-it also should be witnessed and notarized. In addition to delegating specified powers to another person (called the Agent), a well drafted POA also nominates someone (usually, the Agent) to serve as your guardian and conservator should you become incapacitated.
Guardians and Conservators are appointed by the Probate Court. The Court generally looks favorably upon guardianship and conservatorship nominations. Judges, while always reserving the right (and having the duty) to act in the "best interests of the protected person," usually give great deference to an individual's stated wishes.