I don’t use butter in my biscuits. It’s not traditional (poor Southerners couldn’t afford it) plus it is harder to work with - I always use shortening. It’s also got less water in it (less water = fluffier biscuits) and isn’t as hard as a rock when you take it out of the refrigerator, so it cuts in by hand much easier than butter. That means you are working the dough less to get everything incorporated.
Butter comes later - you melt some and brush the biscuits with it when they come out of the oven.
As already said, work the dough as little as possible. You want it to be very soft and a bit wet when mixed. Flour your board, give the dough a few turns (no more than 4), pat it out and cut. No twisting with the cutter, or if you don’t have a cutter, use a very sharp knife.
If you don’t have buttermilk, you can make ersatz buttermilk using milk + lemon juice or vinegar.