"Good character" is too amorphous.
That is one reason I found being at the Mir in NY helpful for me in the emphasis on Musar. Not that they learned a lot of Musar. As compared to the five hour "seder" (session) in the morning of Gemara in depth and the four hour seder of gemara with "bekiut" [fast learning], the Musar was short. It was 20 minutes before mincha and 15 minutes before the evening prayer. That is just 3% of the time. Still that short time was enough to give me a good idea of what "good character" is as defined in Torah.
Maybe some examples might be helpful.
But I am not so sure I am one to be giving "musar". The best idea is to take the basic set of Musar of the Rishonim [אורחות צדיקים מסילת ישרים שערי תשובה חובות לבבות ספר היראה לר''ת מעלות המידות]
But I also should add that this does not work very well without being coupled to the Gemara. By itself Musar tends to go off into tangents. For that reason Rav Haim of Brisk did not want it introduced into the yeshivot. But to Rav Israel Salanter, Musar is importnat for everyone. So eventually a kind of sytheneis came about when there is now short sessions of Musra in Litvak yeshivas. Not too much. Not too little. Just right. [Goldilocks.]
