Hi Jonna, They do get leggy when they don't get enough sun but will get a bit bushier when cut back. After pruning, new branches will sprout just below the cut ends. The cuttings root easily and can be placed with the mother plant to make it fuller also. When I prune my little plant I let the cuttings lay out for a couple of days so that the cut ends dry and callous over a bit before planting them up. My African Milk Bush looks a bit pitiful right now from lack of care. I rooted a lot of cuttings last year all in the same little pot and it made a nice gift plant for a non-gardening friend who wanted to try her hand at succulents.
This first picture shows the new branch that sprouted below the cut, the second is a little plant in the same pot from a cutting that I just stuck back in the same pot with the mother plant.