1. Press quilt with dry iron.
2. Measure quilt through middle (vertically and horizontally)
3. Add 2x width of that measurement and cut border strips to that length
4. Attach top and bottom borders
5. Attach side borders[/quote]
Were you adding 2x width for mitering?
I also try to remember to compare the length of the sides and the length of the ends. If one of the sides is longer than the other side (same for ends) a correction could be made. Maybe just squaring up the corners would help.