Here are a few tips to help you find the right fit for your body and avoid unfortunate corset flaring and gaps.
Evaluating the Fit of a New Corset – Part II; Proper Torso Positioning of the Corset
Corset fitting help? Details on comments. Patterned from 1890 Symington wasp-waist corset (last picture) : r/HistoricalCostuming
WHAT DO DIFFERENT CORSET LACING GAPS MEAN?
How to make and fit a corset mockup
MORE CORSET FITTING ISSUES: Troubleshooting + Clarification
Addendum to “Corset Gaps”: troubleshooting more corset fitting issues – Lucy's Corsetry
First corset, opinions on how it fits? : r/corsets
Military Style Zip and Buckle Corset
MORE CORSET FITTING ISSUES: Troubleshooting + Clarification