Look, here's the thing. Tourist Paris around Champs-Élysées and Trocadéro is designed to separate you from your money. Skip these completely.

Seine river cruises. Overpriced tourist boats with bad food and worse wine. You see same stuff walking along quays from Pont Neuf to Île Saint-Louis for free. Save your €20 for real bistro meal.

Expensive restaurants near Eiffel Tower or Notre Dame. Any place within 200 meters charging for location, not food. Walk 5 blocks toward République or Marais and eat better for half the price.

Hop-on hop-off buses around Arc de Triomphe. Paris isn't that big. Use Métro like human being. These buses get stuck in Champs-Élysées traffic and you see nothing but other tourists.

Perfume shopping duty-free at CDG. It's not cheaper, they just want you to think it is. Buy perfume in city around Saint-Germain if you must.

Here's what to do instead: walk along Seine, eat where locals eat in République, use Navigo pass. Paris isn't expensive if you're not stupid about it around tourist zones.