Make sure you have a clean sharp blade and shave using short strokes. It is important to shave in the direction of your hairs' growth, which means down on the cheeks and chin and upwards on the neck. If you are not sure, run your finger across your stubble to see which direction the hair is growing. Shaving against the direction of hair growth is the primary cause of razor burn, redness and rashes.
Using an all natural shaving oil can also help reduct redness and razor burn by helping with the proper lubrication for a smooth shave.