I will introduce several good places to fight monsters in the free worlds. The challenge that you will have is finding a location that is not swarming with other players. These other players might be Kser's or Kill Stealers. These are n00b players who try to take the monster that you are waiting for to re-spawn. It doesn't matter what level these players are, they are by definition a n00b (n00b is a new player who is obnoxious and inconsiderate, always lacks respect for others and is ignorant to proper gaming etiquette). These players are different than newbs which are simply new players to the game or to the area.
If someone starts Kser?ing you, politely ask them to stop. Don't get into a flame war with them; it will do you no good. If you are much stronger than them, take every single kill that is available by fighting one monster and maging another before your original dies. You can also attack one monster until it is more than half way out of life, stop fighting it and attack another. Keep on doing the same thing to all the monsters until there are no more left. Now no matter who finishes the kill, you will get the . Only do this in a situation where others are impeding upon your area and being jerks about it. If you are not as strong as the other player and he will not back down, your best bet is finding another server with fewer players on it. When I first started playing there were only 2 worlds and if any world had more than 2000 people on it at a time, the server would crash. At least now you have the option of going to one of almost 90 worlds.
If you are going to use combat to make money you are going to have to increase you in this skill. The higher your level, the better (much better) the pay off.