Start from their account of it, not yours
The most useful thing you can offer early on is an accurate picture. Ask what a bad day actually looks like, what has changed, and what they have already tried. Repeat it back in their words. People who feel understood are far more likely to accept practical help later.
Offer options, not instructions
"Would it help if I booked it, sat with you while you rang, or did neither?" leaves the decision where it belongs. Instructions tend to produce either compliance without commitment, or a row. Options preserve their sense of being an adult in charge of their own care.
Take over the admin, not the decisions
Forms, phone queues, transport, childcare and reminders are legitimate places to step in — they are effortful and they are not personal. Choosing a treatment, disclosing at work, or deciding whether to accept a referral is theirs, even when you would choose differently.
Say what you can do, and what you cannot
Support that has no limits tends to collapse. It is kinder to say "I can do Tuesdays and I can answer the phone in the evenings" than to promise everything and withdraw later. Being clear is not abandonment.
Expect slow, uneven progress
Recovery in mental health is rarely a straight line, and a bad week is not proof that nothing is working. Watching for change over months rather than days protects both of you from discouragement.
Look after your own health
Supporters get exhausted, and exhaustion looks like irritability and hopelessness long before it looks like tiredness. Your own GP appointment, your own sleep and your own time off are part of the support plan, not a distraction from it. Carers' assessments are available through your local council in England.
Where your role ends
You are not their clinician and you cannot carry the risk on your own. If you are worried about their safety, involve real services rather than trying to manage it privately.