A continuation of my post from last time, I give you my ideal beta test. Much like communism, this will look great on paper but not come close to working properly in reality. Just for sake of argument, we'll assume the game that is being tested is an MMO as those tend to be the games which provide beta tests the most often and with a full scope of the game, while most other games are beta tests of multiplayer material. To start, you have to have the right balance of players, ranging from casual players to hardcore 'raiders' and ranging from PvP fiends to PvE carebears, but that's only the start.
A test should have equal amounts of testers from all categories, regardless of the proportion of their preferred content that a team is wanting to put into a game. The reasoning behind this is that regardless of who your 'target' audience is, you want to have equal amounts of feedback during the testing phase so that all elements of gameplay are represented. Speaking of feedback, beta tests should feel free to annoy their testers with surveys and feedback requests. Feel free to remove testers who do not provide feedback and reports, after all, while you want a game to be hyped up and you want public interest, you don't want to be providing an early 'demo'. Which brings me to another requirement for testers: they should be able to answer some basic questions about the game before they get entered into the test: simple things like the name of the factions, the name of the continent, and featured aspects of gameplay.
This knowledge should be easily found from a game's webpage or social networking. If somebody wants to test, they should have at least a base understanding of what they're getting into. This provides an incentive for potential testers to do a little reading about a game instead of just filling out their requested username, password, and e-mail address. If a tester is not willing to know a little bit about what they want to test, there is little reason to believe that they'll ever submit feedback or participate on forums. The content of a beta test needs to be carefully selected and done in controlled stages.
No need to emphasize PvP or PvE content one week over another, that will just cause players to no show up, or ignore the content that they don't enjoy. Instead, set each bit of content to a theme, a zone, a level range, or some other aspect of the game. Erase beta characters frequently but provide many template characters to choose from while giving a moderate amount of customization so that players can still experiment and attempt to 'min-max' your game, to work the loopholes, and glitches in coding. This kind of rolling and changing experience will hopefully keep testers coming back without subjecting them to the same content again and again. Coming from personal experience, there's not much fun in running the tutorial and low level content of an MMO again and again.
Finally, implement some kind of personal beta journal and require players to provide a brief summary of the content that they tested and a review of that content. READ these journals, even if it's a quick skim through to make sure you've not missed something. Remove testers that do not provide a decent journal entry regularly. Again, you want testers that are working together to test, not a bunch of people wanting a sneak peek at a game before it's release.
It should go without saying that this would be for a close beta test. Once the NDA is lifted and an open beta is started, the gloves come off and the floodgates open. See if your servers can handle the strain, watch the unwashed masses do everything they can to skip content, glitch out encounters, and otherwise run roughshod over your game. In my opinion, that's the whole point of an open beta. It's like letting a classroom of toddlers play with a new toy; if it can survive that, it can survive anything.