Common knitting mistakes
Count first, then inspect the row where the fabric changed: unwanted yarn-overs add stitches, dropped loops remove them and twisted stitches tighten them.
Work the technique
Spread the row on the cable. Follow each column down to locate an increase or drop. Undo one stitch at a time by putting the left needle into the loop below before letting the current loop off the right needle.
Try it on a sample
In a 20-stitch sample, make an accidental yarn-over and identify the hole it creates; undo back to that point and rework.
Check and recover
Do not pull out several shaped rows without recording the pattern row. Place a lifeline through a known-good row in lace before repairing above it.