Start any diet with a food diary and record everything - all diet tips, food eaten, exercise, how you felt, more diet tips. That tells you about yourself, your temptations, and the emotional state that may encourage you to snack.
Drink plenty of water. Water itself helps cut down on water retention because it acts as a diuretic, before meals water can dull the appetite.
Substitute activity for eating junk food. When the cravings hit walk around the block, do some housework, read, anything just to take your mind off those old habits.
If you're a late-night eater, eat high fibre carbs such as a slice of brown bread orwholemeal cracker biscuit before bedtime to cut down on cravings.
If you use food as a reward, establish a new reward system maybe buy yourself a non-edible reward.
If tempted by a treat, you could eat half then throw the rest away.