Eating too much chocolate and sweets

Ok, so i eat a few bags of crisps, sweets or chocolate most days (but not every day) of the week and i have a few glasses of fizzy juice two or three days a week. I don't want to completely cut fizzy juice and sweetes out my diet but i want to be able to cut down on the amount i eat.
I am thinknig about having two days a week when i can have one or two glasses of fizzy juice and one or two days when i can eat anything i want (with moderation), the rest of the time being as healthy as possible. Has anybody tried this or another way of reducing my need for sugar. Although i know that each person is different, any ideas would be useful so i can try some out and see what works for me.