How do I compress mp3 audio file to small size?

I've compressed plenty of MP3 files over the years, and here's what works for me:

Quick tips:

1. Use (free) or online tools like https://compressexcel.com/whatsapp-audio/ compression and MP3Smaller - they're straightforward and get the job done
2. Lower the bitrate to 128kbps or 96kbps for smaller files - anything lower starts sounding noticeably worse
3. Always keep your originals! Once compressed, you can't recover that lost quality
4. Test one file first before batch converting - you don't want to ruin your whole music library

The main downside? It's a trade-off between file size and sound quality. Compress too much and it'll sound tinny or flat, especially with bass-heavy music. Also, converting takes time if you've got hundreds of files.