Without the risk of failure there is no risk of success. You need a balance of positive reinforcement and negative punishment–too much in one direction is a bad thing. For the most significant feelings of accomplishment, there must be significant risks and significant punishment for failure (not that I’m necessarily recommending significant punishment, but the more significant the punishment for failure, the more significant the psychological reward for success).

Players are the x factor of MMOs. If a player can do it, they will do it. They will behave badly if you let them, they will exploit if you let them, they will ruin the experiences of others if you let them. It’s best to mitigate undesirable behavior through reward/punishment or by altering a system’s design to prevent it. But, while heavy-handed artificial restrictions should generally be a last resort, sometimes they are unavoidable.

Finish your game before launch. If the launch date can’t be pushed back, remove the unfinished portion of the game and get it done right. For example, if the last 20-30 level chunk of your game has (basically) no quests, and quests were previously the method to gain levels, change the level cap to end when the quests end. If the content can’t fill out as many levels as the mechanics, you pretty much have to go with the weakest link and temporarily lower the level cap.

If a decision can logically be altered, let the player change their decision. Certain aspects of a character are essentially set in stone in most fiction, such as race choice; these aspects don’t need to be changeable. But, anything that makes sense to change (and is technologically feasible) like talent or achievement choices should be alterable by the player later in the game. Other examples are hair style choices, faction selections (depending on their importance in a game), and where their home recall point is.

Players should be making informed decisions. If a player is asked to make a meaningful choice, such as selecting their class or race, they must be informed. Give them all the information they need to ensure they’re making a “good” choice (in their perception), or they’ll be anxious about making it in the first place. This applies at every step along the way, particularly if the choices are permanent, and it can be quite tough to do effectively at character creation. But, whenever a player is making a decision, they need to know what the consequences and possible outcomes are before they are asked to make it.