If this is the first time you plant lithops seed, maybe you can following our seedling method as below :
Euphorbias are very easy to care for. They require a little pampering to become established, but once they are, they are self-sufficient. In fact, more die from too much care and watering than from neglect.Euphorbias need well-draining soil and lots of sunlight. They are not particular about soil pH, but they cannot tolerant wet soil. Unlike most succulents, Euphorbia does not handle long periods of drought well. It may need weekly watering during the summer. Water whenever the soil is dry several inches below the surface. Water deeply, but don't let them sit in wet soil, which can cause root rot. Add some organic matter or fertilizer to the planting hole. If you are growing them in containers or your soil is poor, feed with a half-strength fertilizer monthly.
Euphorbia can be grown from seed, but they can be difficult to germinate