Plant a variety of hedges, trees and other plants surrounding your front porch to add privacy. These plants do not necessarily need to be on the edges of your front porch. Instead, they can be placed on your property line, to add privacy without making your front porch feel claustrophobic.
Hang potted plants along the perimeter of your front porch. The plants screen your front porch, without blocking too much sunlight from reaching it.
Add lattice panels to the sides of your front porch and allow ivy to grow on them. This adds privacy, while still allowing your porch to breathe.
Add a fence or wall along the sides of your yard. This limits the view of your front porch from the sides, but allows you to still enjoy a view looking out the front of your front porch.
Add blinds or curtains to create a porch that feels like a room added onto your house. Depending on the amount of privacy you prefer, you can open or close the blinds or curtains to your liking.