A General Confession is a confession that we do from the very beginning of our life or from our last General Confession. There can be many good reasons to do a General Confession. One reason can be that we convert to God and we are not sure that our past confessions were good for lack of a proper accusation of our sins, for lack of a sincere contrition, for lack of a firm purpose of amendment, or because we doubt the proper ordination of the ministers of the Novus Ordo. I would advise anyone who joins Tradition to do a good General Confession of all his sins. Another reason could be the desire that we have to better accuse our sins or to renew our contrition of having committed them. There is no doubt that God is granting special graces to those who do a General Confession of their life.
To do a General Confession, one should take a good Examination of Conscience and make a list of his sins in writing, taking a special care to list all the serious sins of his life, with their species and number, as much as one can remember the numbers. (If we do not remember the numbers, we should give the priest some idea by saying for example: during two years, I committed this sin often…) We can examine our conscience one commandment at the time, or by investigating each period of our life, remembering places where we lived, people we knew, etc.