The first week with a client decides how much they will cost you for years. Almost all recurring support load traces back to something that was never established at the start.
Find out who is who
Ask two questions before anything else: who is technically responsible, and who pays.
These are often different people, and occasionally different companies. A support request from someone with no authority to approve a change, or a suspension notice sent to a developer who does not handle invoices, each cost a day.
Record both, with contact details, and note which one you take instructions from.
Establish where the domain is
The most common reason a launch stalls is a domain nobody can log into.
Ask early: which registrar, who has the account, is there a transfer lock, is the contact address on it still live. If the registrar account belongs to a former developer who is not returning calls, you need to know that in week one, not on launch day.
Moving a domain between registrar accounts goes into the recovery route.
Agree what is included
This is the item that prevents the most trouble and takes the least time.
Hosting is a server. Whether it also includes fixing their WordPress, migrating a site, writing DNS records for a third-party service, or answering questions about their email client on a Sunday is a decision, and the client has already assumed an answer.
State it plainly, in writing, before the first invoice. "Included: the hosting, account setup, one migration, and hosting-related support. Billed separately: work on the site itself." Deciding what support to include goes into drawing the line.
Set the contact address correctly
The account's contact address must not be a mailbox on the account itself.
A full account cannot receive mail, so the warning that it is nearly full is refused by the account it warns about. Set it to an external address during setup, when it takes ten seconds. For which notifications to keep, see cPanel contact information and notifications.
Decide at the same time whether warnings go to the client, to you, or both. Both is usually right for disk; you alone for anything they cannot act on.
Send credentials sensibly
Whatever route you use, the password should not live permanently in an email thread.
Set a temporary password, send it separately from the username, and ask them to change it at first login. Better still, have them set it themselves.
And tell them clearly that you do not need their password to help: you can reach the account from WHM. That single sentence prevents the habit of clients emailing passwords whenever they have a problem, which is a risk you inherit every time it happens. Opening cPanel from WHM without a password explains your side.
Migrate before you point the domain
Get the site running on the new account and testable before any DNS changes, so problems are found while the old site is still live and nobody is affected.
Lower the domain's TTL a day ahead so the cutover is quick when you do it. Planning a DNS cutover deals with the sequence.
Check the boring things before handover
A short list, run every time: the certificate covers both the bare domain and www; email sends and receives in both directions; a backup exists and has been restored once; the contact address is external; the site loads on a phone.
Each of these becomes a support ticket if missed, and each takes a minute now.
Write the summary
At the end of the first week, send one message stating what was set up, what is included, what is billed separately, how to reach you, and what to do if the site goes down.
It is fifteen minutes. It is also the document you will refer to in every later disagreement, and having it written at a moment when both parties are happy is worth more than any contract clause added afterwards.
What to include in your hosting terms goes over the formal version, and reseller best practices deals with the wider operation.
Collect the things you will need later
Several items are easy to obtain at the start and awkward to obtain during an incident.
A second contact who can authorise changes when the first is unreachable. A billing contact if it differs. And an out-of-hours route for genuine emergencies, with a stated definition of what counts.
The one people skip is the second contact, and it is the one that matters: an account whose only contact is on holiday during a compromise leaves you deciding alone whether to suspend. Suspending accounts explains why that decision has a clock on it.
Record where everything actually is
Registrar, DNS host, mail provider, payment gateway, and any third-party service the site depends on.
This takes ten minutes at the start and is close to impossible to reconstruct later, particularly after the developer who set it up has moved on. It is also exactly the document whose absence creates the situation described in inheriting a website nobody documented.
Store it where a colleague can find it, not in your own notes. The value of the record is that somebody other than you can act on it.
Set the expectations that prevent tickets
Three things said at the start remove a disproportionate share of later friction.
What your response times actually are, including out of hours. A client who expects a reply within the hour and gets one the next morning is disappointed by a mismatch rather than by the service.
That you will never ask for their password. This both protects them and stops the habit of emailing credentials.
Where outage information appears. A client who knows where to look does not write to ask. Telling clients about maintenance and outages sets out keeping that channel consistent.
Check back after a month
One short message at thirty days: is everything working, is there anything unclear, is the email set up on all your devices.
It costs five minutes and it surfaces the problems clients have not bothered to report, which are frequently the ones that turn into dissatisfaction rather than tickets.
It is also the natural moment to notice whether this client is going to be profitable, while the relationship is new enough to adjust. What support to include and what to charge for deals with making that adjustment early rather than after a year of unbilled work.