Recipes
The simplest recipe involves merely beating a few eggs into warm water. You can add pepper, Tabasco, garlic, cloves and/or milk to this mixture and let it steep for a while, as these tastes are offensive to deer. They will avoid plants with this mixture on them.
Application
The most effective method for application is to spray your plants and trees with the mixture. This will get the most range out of the mixture. You can also set cups with the mixture in them around the perimeter of the garden. You can spray or pour the mixture on the roots of trees for maximum potency. If you spray your garden, be sure to reapply any time it rains.
Considerations
The smell of the egg mixture can be particularly offensive to you or your neighbors, since the eggs will eventually rot. If the odor becomes overwhelming, you may want to look into commercial deer repellent, available at hardware stores and online.