Just let the mind wander and run around and do all the things it wants, after a few months of these the mind will settle and then focus is possible. Think of it like a child it needs to explore and tire it's self and feed it's curiosity. Think of the mind as a lake, and thoughts as waves. The waves need to play out and then become one wave. When they have become one wave then much more focus is possible. Then next to calm the water and see clearly what is at the bottom. When thought comes up it is like a whole wave of ideas. These settle at the bottom, and can be called upon.
Also note mind
yoga is the 2nd limb of yoga and not to be done before the first which is the physical yoga, the philosophy of development maintenance and well-being of the physical body. If you are having trouble focusing and clearing your head you likely need to be more grounded before continuing with the mental work. Also note it is incredibly dangerous to do the mind yoga before the physical body is ready to handle the mental energies coming through it. If the body is not sufficiently developed in can be ripped apart by the energies coming through it that are a part of mind yoga. More commonly one can go crazy from not being grounded thinking the mind should control their life not physical realities. This is also a large part of why the physical body deteriorates. The body needs to be developed to a state where it can handle long sitting mediations without deteriorating or decay sets in and the soul is set back to square one.