Rule number one here has to be to shop around considerably when you are contemplating a trip. It is not usually a good idea to focus on just one destination and then accept the lowest price that you can find. Instead, try compiling a list of around 20 plus destinations that you would love to venture to and keep your eyes peeled for all of them.
Then you need to weigh up a few other factors: First, look into the best exchange rates today and try to ascertain which destination is going to provide you with the best value for money. This would obviously mean that it will cost you less for the accommodation, once you get there and you will also save a lot of money on your food expenses.
Next you need to price up the cost of flying to said destination. Obviously, the best deals will be when you book in advance, but not too far beforehand. It is a fallacy that you get the best deals if you book more than 6 months beforehand - you won't! Airlines try to get high prices to start and then will reduce when seats are not selling quite so well. About 3 to 4 months before departure seems to be a good rule of thumb.
You can book the accommodation through a discounted agent before going but you will often find good deals by booking directly with the hotel. Especially if the rate is good and this has not really been taken into account through the agency site.