The biggest abuse at almost every parish is the nearly 100% reception of Holy Communion by the congregation in parishes that have minuscule Confession opportunities and lines.
I would think that the Communion Fast from food before reception should be increased from one hour to three hours. This would make it much more likely that many parishioners would not be able to keep the fast and if they were adequately catechized, they would not want to receive Communion.
This requirement and that of being free from Mortal Sin should be announced by the celebrant immediately before Communion in every Mass for several years before the habit of sacrilegious reception can be minimized. [A similar announcement is generally given at Christmas and Easter Masses and at marriages and other events where large numbers of non-Catholics might be present].
Ushers should cease guiding communicants "row by row" up to the front. Let them go up as they want, or don't want. Then it won't be so conspicuous if some don't receive, putting an end to idle speculations as to which mortal sin ones neighbor or pew-mate had committed.
Confession opportunities must then be increased for parishioners to more than just 30-60 minutes before the Saturday Vigil Mass.