The gemara brings situations where people were too happy at a wedding and the father of the groom (a rabbi) broke an expensive item to cause people to be sad. Tosafot say that this is the source for the custom to break a glass at a wedding. One must judge or learn before prayer as it will be distracting but one should learn a simple clear cut halacha like the chumra of women to wait seven clean days after seeing any blood or a leniency for tithes in order to feed one's animals without having to tithe the food or a law regarding misuse of consecrated property regarding blood of a sanctified animal.  One should part with a friend with words of Torah. When Rabbi Akiva prayed with the community, he shortened his prayer so as not to inconvenience people and when he prayed alone, he bows many times. Many things are learned regarding prayer from Daniel, Shlomo and Chana. The gemara derives all sorts of laws about behavior and prayer from Chana. They also teach about sensitivity to barren women and how difficult their struggles are. According to one explanation, Chana thretened God that she would become suspecte dof being a Sotah in order to get the reward given to an excused woman who is innocent of bearing children.