There are three ways to accrue points in MUD. By far the most popular is to wander around looking for treasure, and, when you find some, taking it to the swamp and dropping it (a process known as "swamping" the object). This will score you points equal to the value of the object. You can then go off searching for more treasure. Swamped objects are effectively out of play until the game is reset, unless the powers that be "unswamp" them.
The second way to get points is by doing certain actions. For example, deep underground is a 'fountain of wisdom', and entering it will get you a considerable number of points. Needless to say, getting to it isn't all that easy! Eating food is another good way to get points.
Finally, there's fighting. You get points if you kill someone or something in a fight, or if they flee from the fight. The rewards of fighting are immense, and the higher-ranked players can be worth many thousands of points if killed. However, it is also very dangerous, since if you are the one who is killed you will lose ALL your points, whether you started the fight or not. Even if you win, you will have made yourself an enemy (even the non-players you fight will remember, at least until the next time the game resets!). Fighting players is a high-risk, yet potentially high-return, business.