Join PRS first via their website. Once approved, register your songs through the online portal, providing song title, co-writer information, publisher details, and splits. For MCPS, if you're self-published, apply separately and register the same works. Registration requires accurate data: full legal names, IPI numbers, and percentage splits totalling 100%. Register songs as soon as they're complete - you can add ISRC codes later when recordings exist. Both societies use the same online portal for work registration.