What steps can I take to get a POA, Conservatorship, or other form of control over my mother who is making very poor decisions with money?

From what I know, in doing Mom's PoAs, your mother would have to be of sound mind and be willing to sign documents. You may approach her by saying that she just needs a "little help" with handling finances and you are doing this to protect her assets from unscrupulous people (and, believe me, those people walk among us.) I would only get the courts and the doc involved as a LAST resort.
I downloaded PoA forms (both medical and financial) from a website called: Legacy Writers. Their forms are updated as per your state's requirements (very important). I would recommend printing out several copies and have them all signed because the doc, hospital, and NH, etc. all want original copies. Then have all copies signed, witnessed, or notarized as your state recommends. I also like that they keep your docs on file for several years in case you need add'l copies.
Another thing that really helped me, was signing up for an online account with Mom's bank. I can monitor her accounts, pay bills, or move money around.
If your Mom is getting careless with her finances, you owe it to her to step in.
Good luck

Thanks for your help! I have not asked mom yet if she would approve of a POA, but she and I get along quite well, but I don't know how she will react. For some reason I get the hunch she is suspicious of my brother and I and I know they can get that way. We are the ones trying to help, yet she can give thousands to a scam artist contractor without blinking an eye -- never called us to check with us first either before signing off with this jerk. Our hands right now are tied. She can spend as she pleases. Very frustrating.

First - call the cops, better business bureau, local contractors association - any PROFESSIONAL about the contractor and then ask the them to talk with your mom about him and his practices. They might help her understand that she's been conned which - we'll hope - will mean she turns to YOU instead.

I got my parents PoA specifically so I could do their banking in case they had an emergency. Perhaps that's how you might approach your mother. Be advised that to do this, you will have to be put on her bank accounts at some point - you must do that WITH her at the bank, a PoA is often not enough to get signature authority on her accounts. It will give you authority to set up direct deposit with payees to OTHER accounts in your name.

You might have to work on it over a few months to get her to sign a PoA and/or add you to her accounts. Begin by helping her balance her check book, or ask to review her bills to ensure she's not getting scammed. This is manipulative - which I normally hate - but since it's in her best interest I think it's okay. Tell her that you've had trouble with the phone company - someone added services without your permission and it hiked your bill up by $50 a month - or something like that. If necessary use the cable TV bill or electric bill - anything to start a discussion about her financial safety. Tell her you've heard on the news about scammers calling on the phone and ask if she feels she's been targeted.

I've had my parents PoA for more than 20 years and it's something I take very seriously since I have brothers that might cause legal trouble. I am also very diligent about making mom's remaining money last as long as possible. I keep every receipt, a log of decisions and my rational for making those decisions. There are various forms of PoA - a DURABLE is the most powerful and covers everything. She can also assign specific PoA, for example, banking only and might include an expiration date. if you want to make decisions about her medical care, it's best that she do a living will or medical directives and a medical PoA.

At 83 I'd suspect that she's struggling to retain control of her affairs. She might realize that things are getting complicated but doesn't realize it's due to her memory. She's likely to think that her problems are caused by others - it's denial and very common. To have her deemed incompetent is really difficult and would take a LOT of evidence - speak to a local attorney in her community if you're concerned about this. In most states, she'd have to be REALLY bad off and have a tragedy - like loose a LOT of money - before something like that is possible.

Best of luck.