Good Fortune
An old Scottish belief for good fortune: A bride should be met at the door after the wedding ceremony by her mother, who must then break a currant bun over her daughter's head. 

A kiss from a chimney sweep is supposed to bring good luck as he has magical associations with the family - the hearth of the fire symbolizing the heart of the family. 

A horseshoe carried by the bride is considered a symbol of fertility. 

Bad luck for the bride who looks in the mirror wearing her complete outfit
before her wedding day - old beliefs say that part of yourself goes into the reflection and therefore, the bride would not be giving all of herself to her new husband. 

Carrying The Bride Across The Threshold
1.)  The custom of carrying the bride over the threshold stems from the same belief that aroused the idea of runway carpet and strewing the aisle with flowers and petals. It was an ancient belief that the newly married couple was very susceptible to evil spirits. By carrying the bride and supplying a protective layer between the floor and bride, she would be protected from the ground monster. 

2.) Generations ago it was considered lady-like for the new bride to be, or appear to be, hesitant to "give herself" to her new husband, whether or not she truly was. At the threshold to the bridal chamber, the husband would often have to carry the bride over to encourage her to go in.

3.) Tradition dictates the new wife must enter her home by the main door, and to avoid bad luck, must never trip or fall. And from that we get the bride being carried over the threshold. 

4.) During the days of "Marriage by Capture," the bride was certainly not going to go peacefully into the bridegroom's abode, thus, she was dragged or carried across the threshold.  In even earlier times, it was believed that family demons followed the woman and to keep her family demons from going into the groom's home, she was carried across the threshold upon her entering for the first time.  After that, the demons could not enter as she would come in and go out of the home.