The easiest way to write a power of attorney yourself is to use a do-it-yourself kit. It's true that legal forms can be prepared in Word but only professionals who are aware of the local laws and form requirements should ever prepare one from scratch. When you use a do-it-yourself kit the form is already prepared for you and all you have to do is fill in the blank spots. It also comes with instructions on how to fill in the form, and how to give good legal descriptions. I'll post a link in the related links below to a website that carries DIY power of attorney kits that include instructions and a helpline to call for professional legal consul if you need it. They also have a good reputation partly because their the oldest professional legal form providers on the internet today and you can always expect quality from them.
Unless you are absolutely sure about what you're doing and fully informed about the consequences, you should consult an attorney. A POA grants sweeping powers to your attorney-in-fact. They will have complete access to your assets and will need to be capable of keeping good records. They should keep an account of all the money coming in and all the money going out by their hand. They must be trustworthy, organized, intelligent, reliable and act in a professional manner where your finances and property are concerned.