"Traditionally"? I don't think there is any such thing 
In my experience:
* Most people are poor beta testers. A poor beta tester will cost you effort and will not give much of a good result; poor beta testers are a net negative to your project, as well as a time sink.
* Some people are enthousiastic about playing your game (earlier than the rest of the world). These fall in the category above.
* If people PM their "wish to test", you must therefore judge their "ability to test".
* You don't need a lot of testers. You should test a bit yourself, and having one or two testers aside from you is sufficient (in comparison, most of the beta testing for ATOTK was done by two people)
* Communication is fine by e-mail back and forth. Alternatively, you can make a private thread for these people.
* Pick at least a month, two if it's a big game.
* Update frequently, so that people don't repeatedly fall into the same bugs, and can verify that things are fixed (and no new things are broken).
* Put a decent debug mode in your game. The standard "teleport + stuff pockets" is nice, add whatever else you can code for it.
* It is a good idea to not tell the testers the solutions (to puzzles) beforehand. That way, you can find out which ones are too easy or too hard.
* Golden rule: PAY ATTENTION to everything they say! I know way too many authors who get defensive towards bug reports, and discount them because "it was not intended that way". This is a POOR excuse, and will reduce the end quality of your game.

In my experience:
* Most people are poor beta testers. A poor beta tester will cost you effort and will not give much of a good result; poor beta testers are a net negative to your project, as well as a time sink.
* Some people are enthousiastic about playing your game (earlier than the rest of the world). These fall in the category above.
* If people PM their "wish to test", you must therefore judge their "ability to test".
* You don't need a lot of testers. You should test a bit yourself, and having one or two testers aside from you is sufficient (in comparison, most of the beta testing for ATOTK was done by two people)
* Communication is fine by e-mail back and forth. Alternatively, you can make a private thread for these people.
* Pick at least a month, two if it's a big game.
* Update frequently, so that people don't repeatedly fall into the same bugs, and can verify that things are fixed (and no new things are broken).
* Put a decent debug mode in your game. The standard "teleport + stuff pockets" is nice, add whatever else you can code for it.
* It is a good idea to not tell the testers the solutions (to puzzles) beforehand. That way, you can find out which ones are too easy or too hard.
* Golden rule: PAY ATTENTION to everything they say! I know way too many authors who get defensive towards bug reports, and discount them because "it was not intended that way". This is a POOR excuse, and will reduce the end quality of your game.