Start with working on technique and flexibility first using your normal bi-fins.
Buy a simple monofin, second hand will do! like a Waterway Model 2 Middle distance (medium softness). Don't buy a stiff model if you're starting and don't buy the big model, because you don't have the muscle power nor the coordination yet.
Use plastic or some thin toetips to prevent blisters and spreat and transfer the pressure more equally.
And be amazed by the speed as the tiles will schoot by in a blurr while swimming.
Some people lack the requierd back flexibility, they need to find out if they can work their way to it by carfully dayly warming up and stretching, or choose to remain happy with a good pair of bi fins
Women in general are much more flexible in the hips, and allows them to have a nice stroke even after just a 100m swim with a monofin.
There are related threads on DB.
Have fun!
Love, courage and water,
Kars
