We have carried out our first seedlings in 1993. The method we are using for 3 years now is the following (we apply it for all our succulents).

We use a well drained fine soil (with about 70% fine mineral and 30% organic elements) and add a little proportion of vermiculite to allow the mix to retain a good humidity.
Before using it, we sterilise it in the microwave oven (in a covered cup at maximum heat, 10 minutes for about 2 litres soil), let it cool and put it in small polystyrene boxes with drainage holes (L x l x h = 20 cm x 15 cm x 5 cm).
We fill them with about 3 cm soil and the surface is levelled. We soak them in water with a fungicide until the soil mix is completely wet, put it out, cover them with a plastic sheet and leave them aside for about 1 day so that the excess of water goes out.

The labels that will allow the identification of the seedlings (personal collection number, species, variety, collect number if available and sowing date) are prepared.
The chosen seeds are displayed on the soil surface (without being covered with soil) and are carefully sprayed with a fungicide solution. The polystyrene containers are placed in small "sowing greenhouses" fit out with small ventilation windows (closed) and put under a 250-400 Watts light for 10 hours a day.

The first seeds begin to germinate in about 3-4 days and it can go on during the next 2 or 3 weeks. We inspect them every day to prevent fungus apparition (very rare with the technique of sterilised soil, but it may happen that fungus develops on the seeds themselves).
Fine washed and sterilised sand is added at the top of the soil to stabilise the young seedlings.
If some seedling are lying, we straighten them with a toothpick and pull them a little bit in the soil.
The soil needs to stay always humid without being soak.
About 1 month after the apparition of the seedlings, the windows of the " sowing greenhouse " are opened gradually to allow air circulation (we completely remove the cover after about 3 months).

The seedlings grow and begin to ‘compete’. When they have 4-5 leaves (between 6 months and 1 year), we repot them in bigger boxes or pots (after having cleaned them and allowed to heal for 2 days). 3 days after repotting they are watered again.

At this stage they are placed in the greenhouse, being protected from the direct sun and are treated like offsets. The first flowers generally appear 2 to 3 years after sowing.

NB : we generally make 3 series of seedlings per year : in March-April, in July and during winter. It may look curious to sow seeds during winter but under artificial condition, it is possible all year long . We have noticed that the seedlings made during winter could allow us to gain more than one season of growth (for example sown in December and put under artificial light ( about 10 hours/day for 5-6 months) and then put in the glasshouse in May-June for the beginning of the warm days. Our technique gives us very good results and the germination rate is usually from 80 to 100%, depending on the quality and the age of the seeds.

Note about the water :
we use rain water which is collected in a non polluted area and have obtained better results than when we were using "city water" in the past. In case "city water" is used it is better to leave it in open containers for a few days in order to eliminate the possible chlorine.