The best way is not buying too much food. If you have plenty of food in the fridge, you will always think about when, how, who with to finish them.It also effects on your saving too as an average family in England throw away £400 food monthly

Never finish the leftover. If you invite friends around for dinner and one of them can't make it at the end, it is wise to put the extra away before you lay the table or you are likely to eat more than you plan. Don't make yourself a rubbish bin. You'd better keep it for a packed lunch tomorrow.