Registration is the beginning of the obligations rather than the end of the task. Most of what follows takes an afternoon each and none of it happens automatically.
Open a bank account in the company's name
First, because everything else assumes it. Take the registration documents, the identity documents of the directors, and proof of address; banks vary in what else they want, so ask before you go.
Then actually use it. Running company income through a personal account undermines the separation you just paid for, makes the accounting substantially more expensive at year end, and is the single most common thing that has to be untangled later.
Sort out tax
The company is a taxpayer in its own right. Understand what it must file and when. Note the financial year end you chose, because everything hangs off it.
If you will have staff, register as an employer and for UIF before the first payday rather than after. If you will import or export, that is a separate registration too.
VAT is not immediate unless you expect to cross the threshold quickly — but know where the threshold is, because registration is compulsory once you pass it and lateness is expensive.
Set up the books from day one
Accounting software, or a bookkeeper, or at absolute minimum a disciplined spreadsheet and a folder for every invoice and receipt.
Retrofitting a year of mixed transactions is the most expensive thing you can ask an accountant to do, and it produces a worse result than doing it properly as you go — because expenses you cannot evidence are expenses you cannot claim.
Put the annual return in a calendar
On the anniversary of registration, every year, with a reminder two weeks ahead.
This is the single most common avoidable failure in South African small business administration. Companies get deregistered for missing it, and the owners find out from a frozen bank account years later. It takes ten minutes to prevent, now.
Check the registered address and email
These are where official notices go, and they are treated as delivered whether or not anybody read them. Make them somewhere you actually monitor rather than an accountant's office or an address you have since left.
Get the documents together
One folder: registration certificate, the founding document, tax number, bank confirmation letter, and — once you have staff — the Compensation Fund letter of good standing and your B-BBEE affidavit.
Every supplier application and every tender asks for the same handful of documents. Having them in one place turns a two-day scramble into a ten-minute submission, and you will be asked sooner than you expect.
Then go and find customers
The administration is necessary and it is not the business. Set it up properly in a week, put the recurring items in a calendar, and spend the rest of your attention on the part that produces revenue.
General guidance, not legal, tax or financial advice. Requirements and thresholds change; confirm the current position.