A lot of brides ask me what kind of hairstyle should they do if they have medium-length hair. If you have medium-length hair I would definitely suggest doing something that was up, all the way up. You would be surprised how full and how long you can actually make your hair up here in an up style.
Somethings to consider would be braids, maybe throw in some braids and then really kind of puff and expand those braids out so that they were really, really full-looking.
Anytime you add fullness, it automatically makes the hair look long.
Curly styles are also great if you have that medium length hair because it adds a lot of body and movement to the hair, again, alluding that maybe you have longer hair.
Another thing to consider would be hair extensions.
There are some really great clip-on extensions available to you. Try some out, play around with your hair. See if that helps.
Most red carpet looks that you see have added in extra hair extensions. So most people's hair aren't as full and as long as you might think that they are.
So those are some great ideas if you have medium length hair.