Run naked, or not. If you choose, not, then read on. Apart from the running shoes and socks, which have been dealt with elsewhere on this website, the minimum you’ll need for running will be a pair of Speedos or Speedo one-piece or bikini. Don’t laugh, that’s what serious triathletes wear on occasion.
For the rest of us there is immense choice of clothing, or if you’re up-market, apparel, that can take you from drab and messy to the finest chic and slinky designs. To be honest once you’ve got decent running shoes to protect you from negative compensatory patterns, you can run in anything, but your level of comfort may well be compromised. Jeans and cotton T-shirt are not a good choice. In fact cotton is not a good choice, period. Once soft cotton collects moisture from your sweating body it can’t wick it away and becomes abrasive to your skin. Think nipple rash and inner, upper thigh rash. Not comfortable, let’s not go there.
Let’s start by thinking Seasons, Climate and Geography of where you run.