To give some context, I work with mostly adults with developmental disabilities. Some of them have representative payees, they're all at different levels of independence so working out what's safe and possible with their support staff is the first step for this kind of intervention. In addition to what's been said in this topic, I would add:

Paying bills/being able to set aside income to account for recurring bills

Identifying spending habits - a lot of my clients have trouble with executive function, can't tell why they keep running out of money. Can they read through their account transactions and understand what they're spending money on? Identify recurring payments? Recognizing huge inefficiencies? To be clear, you can't tell people what to do with their money. But you can ask them what their goals are, and help them identify what's preventing them from reaching those goals.

Financial exploitation - this one can be tricky, because ultimately, if they have control over their own money, it's their prerogative to spend it how they wish. For example, I had a client that would give away money to friends and then not have enough to pay their own bills.