I love biscuits and have made many. The one thing that gets me is cutting the butter. I have used several different approaches with varying degrees of success. What works for you.
I love using a pastry cutter, something like this:
It does the best job cutting butter or shortening into flour. Every now and again while using it I use a fork or butter knife to remove the big blockages.
I used to use a pastry cutter, but it was hard work and a pain in the butt clearing the blockages. So I switched to using a food processor.
It's so much quicker, and providing you cut the cold butter into 1x5cm sticks, it yields perfect results with just a few pulses.
I usually use my hands, working on soft butter chopping small pieces with my fingers.
One, cut up your butter into small cubes, then freeze it on a plate. The colder you keep the butter the better the result. Then, if you have one, use a food processor to cut the butter into the flour. I don't have one, so I use a cutter, then finish it with my fingertips. If I feel the butter is getting too warm I'll put the bowl in the freezer for a few minutes.
I've found that as important as the cutting is the flour I use. The lower the protein content the better. That, and work the dough as little as humanly possible to avoid gluten chains.