If you have an international credit card, I would just use that. Most if not all places use cards and keeps currency exchanges easy. Don’t stay near the Effiel Tower. There really isn’t that much to do there aside from that. Travel light and simple with comfortable shoes. Trains for everywhere but you’ll still be walking a lot. Also download the Paris map on Google maps so you can use it offline unless you have international data. Before i went, my wife and I pinged a whole bunch of areas to visit and just planned our days according to that. Also for great travel info, look up “traveling to Paris” on YouTube. There are a ton of vloggers that give even better tips than I could.