Analyze his behavior and decide what bad habits would you like to get rid of. Think about how these habits hinder you. For example, if in a stressful situation you bite your nails, your hands will look ugly. If you eat with your mouth open or slurp, it will feel awkward at a table or in a restaurant. If you smoke, you have to spend a lot of money on cigarettes and jeopardizing their health. Think about your behavior and understand why you would like to get rid of his bad habits. Remember it every time you want to chew your nails, smoke a cigarette etc. and stop myself.
Very effective method is to replace bad habits useful. A habit is an action brought to automatism. Select a beneficial habit: running in the morning, daily contrast showers, regular care of your nails, morning exercises, etc. Start to make the selected action regularly and gradually replace the habit useful. For example, if you want to chew nails, think about your new habit to take care of them. Imagine how you achieved the result thanks to its useful habit, as friends and colleagues admire your hands and a great manicure as you do compliments. If you used to get up half an hour before the journey to work, in a hurry to drink coffee and eat Breakfast, get ready fast, start getting up an hour and a half earlier than usual to do gymnastics, to run a bit, take a shower, to eat in peace.
Try to eradicate the habit: stop buying cigarettes, spend a lot of money on a quality manicure, which would be a pity to spoil, etc., Over time, you will be all the easier to forget about your habit and finally it will disappear completely.