There are so many variants. This is one article that I found helpful:
https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html#6DJ8
But ultimately, it is a lot of trial and error.
https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html#6DJ8
But ultimately, it is a lot of trial and error.