The most important thing
The first thing you must know when making cement craft is that the mixture is  liquid. So, you can not play with it like with clay. Having a right mold is crucial. Remember that you can do any crafts that you have a proper mold for. You can use anything as a mold. Try with some disposable plastic glasses if you are a beginner. Choose a bigger and smaller one. Put the cement mixture in the big one. Then, put the smaller on top and push it inside. Wait for it to dry and remove the cups.