Restoring a Mint Condition 1986 525i - Share Your Experiences!

I'm looking to restore my mint condition 1986 BMW 525i to its former glory and I'd love to hear from fellow enthusiasts who have undertaken similar projects. What tips, tricks, and resources can you share for bringing this classic car back to life? I'm interested in hearing about your experiences with parts sourcing, bodywork, engine maintenance, and interior renovation.