When a sole proprietorship is enough
If you have one or two clients, variable income and want minimal setup costs, a sole proprietorship (PFA) is quick and simple to run. Flat-rate or real-income taxation can be favorable at lower income levels.
When an LLC starts to make sense
With recurring clients and stable income, an LLC lets you deduct more expenses, hire without complications, and clearly separate personal liability from the business's. Many larger companies prefer to contract with an LLC rather than a sole proprietor.
What doesn't depend on the legal form
Whatever you choose, you need the same thing: a clear record of clients, projects and invoices. The invoice format and tax obligations differ, but organizing the work stays the same problem to solve.
Bottom line
There's no universal answer, it depends on the number of clients, the size of the contracts and how much you want to invest in administration. Talk to an accountant before signing your first big contract, not after.