Firstly, try to cover your eye with something. Sunglasses are probably the best way to pull this off. Since sunglasses are dark, they will cover most of the bruise once you wear them. Moreover, there are several different shapes and sizes when it comes to sunglasses. If you think your bruise is big, wear sunglasses which fit that size.
You can also wear a cap. A few people might even avoid this since the bruise on the eye is quite visible while you are wearing a cap. However, you should know how to wear it in order to hide the bruise. Try to bring down the cap close to your eyes in such a way that all the shade is concentrated on them. People will hardly notice that you are trying to hide something.
Always use ice in order to bring the swelling down. Apply ice in order to reduce the swelling. It will hurt a lot, but you need it in order to hide the bruise.
If it is winters, then wearing a hood should do the trick. Simply grab a hood and wear it over your head in such a way that it falls right above your eyes. You will have trouble seeing, but you will not have to go through a lot of trouble of using make-up.
Lastly, in order to quicken the process of healing, start taking Vitamin K. You can easily find it in different medical stores. If you are not comfortable consuming Vitamin K pills, then simply eat an orange so you can improve the amount of Vitamin C in your body. Both these Vitamins improve the healing process of tissues. However, in this case you might have to sit home in order to hide your black eye from others.