For now, here's some basic required stuff:
- Up and running Catalina installation
- At least 50GB of free space
- Separate partition
- Penryn and later CPU
- Big Sur installer
- For some cases, USB drive with at least 16GB (you will know when you'll need it)
You can download Beta 1 installer from the link in this post: https://forums.macrumors.com/threads/macos-11-big-sur-on-unsupported-macs-thread.2242172/post-28586298