This is vitally important. I tried to access a completely different type of service a few years ago.
The first person said they were full up and not taking on new clients, they ignored my question about cost. This meant I didn't know whether it would be worth asking them again in a year's time if I still needed help, when perhaps they would have space.
They also asked "have you... xyz?" which was problematic because their question assumed a prior knowledge of the subject, which I didn't possess being only at the very beginning of my journey into it. It was difficult to answer because what they were asking sounded like a general thing, leading me to wonder if they were talking about when this or that happened, but were in fact legal terms relating to specific procedures that I knew nothing about. So when you're talking about decluttering and everything that may come with it such as hoarding, tenancy, social services, therapy, medical help, emotional problems or disability etc surrounding it, don't assume your potential client knows anything about anything and make yourself explicitly clear when asking any questions. If, as I suspect, you know nothing about these additional issues yourself, you'll need to make that clear to your clients. Don't just smile and nod when they talk about things you don't understand. As a professional, clients are likely to expect you to have knowledge surrounding your particular subject and believe you're somebody they could ask advice of, so is important not to give bad advice.
The second person replied to my email about availability and costs with a wishy washy email about having an initial assessment and taking it from there. This was problematic because if I don't know the cost of the initial assessment, how do I know if I can afford it? Moreover, whether I can afford the cost of the initial assessment or not, if I can't afford the cost of the ongoing sessions, there's absolutely no point in even having the initial assessment and it would have been throwing money away.
So please realise you could be dealing with people in poverty who are counting every penny and going without something else to afford your service. They need to know what all the potential costs are.
I gave up and never did get the help I needed and two professionals lost a potential client, totally due to their being unable to put themselves in my shoes and see things from my perspective.
Have you considered all the sensible aspects of starting this business? You'll need third party insurance for if you cause damage to someone's property and possibly professional indemnity insurance, so you don't have to pay out of your own pocket if you cause harm through negligence. If this is to be your only or main income, loss of earnings insurance for if you become sinck, injured or permanently incapacitated and if you have dependant family, life insurance in case you die so they're not left with nothing. If you want a state pension you'll have to pay Class 3 voluntary national insurance contributions, in addition to the Classes 1 and 2(? I think, maybe it's 4? 2 might be PAYE, I can't remember, you'll have to look into it) you legally must pay as a business owner, as these don't count towards your state pension. You'll need to decide whether you're going to keep your own books and file your own tax return or pay a bookkeeper and accountant for those.