It seems easy, but there are some unexpected pitfalls... Here are some tips.Possibilities
There are many many ways of creating MP3 mixes these days. Usually you use your computer's music player; most players offer export features. Although not an Apple fan-boy, I'm using iTunes.Tips
I purchased very few songs on iTunes, protected by DRM. I soon realized it sucks (cannot play MY purchased music on MY other computers). I solved this by burning them (as WAV) to a CD (a CD-RW is great for that) and re-importing them.
Given the capacity of the USB flash drive and the number of songs you want, lossless format will take too much space, so MP3 is the way to go. The quality loss (if you can notice it) shall remind us that, in the cassettes era, "lossless" was hopeless.
I didn't quickly find a player able to export in other formats, and it was a bit late at night to play around with the command line (mplayer/gstreamer), so I found TuneClone which works great together with iTunes. TuneClone pretends to be a CD writer; it intercepts track writings from iTunes, converts them and orders them into a directory of your choice.
I wanted the songs to be playable sequentially (like a cassette) to match the playlist, and importable hierarchically, with artist and album names. So I exported the songs twice:
- all songs in one directory, each song prefixed by a sequence number;
- in a hierarchy by artist / album / song.
Also some players may put "dangerous" characters (from the album/song names) into directory or file names, like quotes, column, semi-column, parenthesis brackets,... It's usually a good idea to remove these characters.
They may also (especially for classical music) produce extremely long names (containing the composer name, conductor, orchestra, soloists, album, movement, tempo, etc.). It's a good idea to shorten them and keep only the essential information.