My first outfit was some random one I joined the day I purchased the game in June 2003. Coming from games like StarCraft and Soldier of Fortune 2, I didn't have experience with a built-in clan/guild/outfit system so I accepted the first invite I got without understanding what it entailed. I left that outfit soon.
Soon thereafter, I became a founding member of the TR SPECIAL FORCES on Emerald. To this day, that period of time was the most enjoyable for me in PS. Unfortunately, the outfit was always s{height}mall and died out when many of the players left for Final Fantasy XI.