Flight tickets

I am a total looser when buying flight tickets. Any time I buy a ticket thinking that the price won't go down, it does, even with Czech airlines. When I wait until the price drops, it always increases. I wish I would understand the price policies! They're really pissing me off! You know, a penny saved is a penny earned.
If fact that's why I like travelling by bus/train - the prices are set or are only getting up.