https://www.edmprod.com/the-ultimate-guide-to-remixing/ Read this article about Remixing!
Free Accapellas . https://www.beatlabacademy.com/remix-or-chop-it-free-acapella-vocals/
This website ( https://splice.com/explore/contests ) has a contest that includes free files. You don't need to join the contest to get the files. User name: ahsimp PW: ahsimp2000
Below are some "starter files" you can use. There are many more on the web. Search "free remix stems" or "free remix contest."
bpm - beats per minute
- setting beats per minute in Garageband
- matching bpm with stems found online
Matching Key - Loops, samples, stems
http://beta.ccmixter.org/stems - a place to find stems - sign up is free
https://www.indabamusic.com/opportunities - a place to find stems - sign up is free
https://splice.com/blog/category/tips-tutorials/routines-process/ song writing prompts and examples
https://www.midiworld.com/files/ A great page for FREE MIDI Files