Less Is More When Making Biscuit Dough
After you cut in shortening, add the liquids all at once and mix until just combined. The dough might not be smooth, but that's OK - it won't affect the outcome.
Knead dough as the recipe directs, just until it holds together. Extra kneading makes dough tough. If dough is very soft, pat it to the proper thickness before cutting, or gently roll it with a lightly floured rolling pin.