To be completely honest with you, the only way to become and remain consistent is to put hours and hours in practicing. By hours and hours I mean thousands. When strong players lose their consistency, it is usually because they have lost that 'inner drive' to practice for hours all day long every day. I've gone through this before. There was a period of time a few years ago where I would practice 8-12 hours per day (I was working at a poolhall), all I thought about was pool, and all I wanted to do was play. It really paid off. Then along came this girl, and that was the end to that. Even now that school is out, I still haven't found that inner drive to go and play all day again. I practice for an hour or two, and lose interest real quick, or lose my concentration. Once you reach a high level (I'm not saying you haven't, I don't know you) and you become consistent, you can maintain that level by practicing less than all day long, every day. 2-3 hours a day a few times a week can help you maintain a high level. For us amateurs, we need much more than that, even to maintain.