This is a small thing, but it makes a big difference for me: Since I have a full-time job and a family, I tend to practice in the evening. Sometimes night. But I've found it's really worth the effort to practice as early as I can. 8:00 or 9:00 at night is fine. But at 10:00 or later I'm really too tired to focus. Practice is much more satisfying when I'm not too tired to concentrate.
Similarly, I can't practice well if I'm stressed out or have other things on my mind. This all might seem kind of obvious, but it was easy for me to allow housework to push my practice sessions very late, and I've now made a point of practicing first, since my housework doesn't suffer nearly so much for me being tired or distracted.