Crystal Reports - Group on a Formula, not on a Field
When creating groups in Crystal Reports, always group on a formula, not on a field (I name my group formulas things like "*G-Job" or "*G-Vendor"; the "*" makes them sort at the top of the list, and the "G" lets me know it's for grouping). Having a formula makes it easy to change the sort order of your report without losing any formatting by simply changing the formula. Once, I spent 4 hours getting a report to look exactly like a paper form, then I found out it needed to be sorted by vendor, not by job and when I changed the group field, all the formatting disappeared, so I lost 4 hours of work. If I had grouped on a formula instead of a field, I could have just edited the formula and not had to re-create that formatting!