How can I be consistently Krishna conscious, without deviation?
Hare Krishna! Thanks for your wonderful question.
First, you should understand that "being Krishna conscious" is a way of life, a way of thinking, not just a series of right and wrong acts. In order to be Krishna Conscious, you have to know something about Krishna; because one thing you must do is think of Krishna and develop love for Him. This is a positive state of mind which requires chanting, reading, talking with persons who know Him and are striving for the same goals!
Association is such an important part of developing love for Krishna and faith in the process that I can't stress it enough. And association goes two ways; good association can help you, and bad association can discourage you and drain your enthusiasm! People who respect what you're trying to do and who are willing to support you are very, very important. Find such people and keep them in your life. Those who try to challenge you and pull you down should be avoided.
Imagine trying to give up overeating while hanging out with people who are always cooking great food and offering you some; it's very unlikely you'll succeed. People who think they're getting their enjoyment from material life will try to get you to think the same way. It's better to avoid their company. This includes TV, radio, and other mundane media that try to attract your mind to sense gratification.
If you gradually take up the process, building your strength little by little, that will also help. For example, begin by chanting one or two rounds each day, early in the morning. Do that for two months or so, and then increase to four, and keep increasing, gradually. Try to keep your schedule of eating, sleeping and chanting regular. Don't eat at night; go to sleep early and rise early. This type of schedule will give you an opportunity to do your Krishna Conscious things before others are doing non-Krishna Conscious things. It will keep you on a different schedule.
There are many other things I can say, but association is most important of them all. So try to come to a temple, meet devotee people in person and on Krishna.com, and read as much as possible; these things will really help. Regulate your life and develop your Krishna Conscious "muscles." It takes time and patience!
If I can be of further assistance please let me know.