Start affiliate marketing with no money - how?

Two things to sort before the first post. Disclose the links, clearly and near the top - in the US the FTC expects it, and readers trust you more anyway. And if you start with Amazon, check their rule on early sales: new accounts that don't make a few qualifying sales within the first 180 days get closed, so it's worth having some traffic before you sign up rather than after.

No money is fine. No audience is the actual problem. The affiliate half is trivial - you apply, you get a link. Getting anyone to click it is the entire job. Pick something you genuinely use and can be specific about, because a comparison written by someone who has never touched the product reads exactly like one, and that's the stuff nobody trusts or shares. Go narrow on one topic instead of building a broad site you'll abandon. Read the programme terms before you write anything, too: some won't accept you without existing traffic, and some hold your earnings until you cross a threshold that could take a year at low volume. And declare the links. It's required, and I've never had anyone leave over it.