Buying the land first and then building on it later allows you more freedom to do what you want with the property, but it likely won't save you money. Be sure to double check that government zoning restrictions won't prevent you from building your dream home on the land you're purchasing.
Alternatively, a house and land package may help you save costs, but will likely limit the amount of customization you can do. This sort of option is often available when a big developer buys a large plot of land and subdivides it into lots for a neighborhood. You may also be limited as to what you can do on your property. For example, you may not be allowed to build a fence, put in a pool or hot tub, or have campfires.