I think the number one issue for a new trader is to learn the ability to take a quick small loss when the trade does not go as expected. This seems to be the hardest lesson to learn. Put another way, the ability to close a trade as readiliy as one is opened.
Once this is mastered, then whether one is overtrading has a lot to do with the style one is attempting. I would say, if you look at your trades, and cannot remember why it was opened (proper research etc), what the criteria for falure/stop was, how it performed vs expectation, (or cannot identify these by style or method), then one is trading too much, especially if capital loss is not controlled, or discipline is not followed consistently.
But if trades are made on a consistent basis, with good research, discipline and capital control, and hopefull profit, then they probably are not overtrading. I say this because the items I mentioned, if done correctly, should keep a limit on trades made, because doing them correctly takes time and effort.
A new trader should keep a log of all this stuff, even a "what was I thinking" notes for open and close. It's a lot of work, but should help identify weaknesses more quickly. The real problem is usually in the mirror.
