To germinate seeds, use a fine mix of 1/3 washed sand, 1/3 cactus compost, and 1/3 perlite OR you can use cactus mix, sold at most retail stores , However, some commercial brands will be too heavy and poorly drained for cacti and succulents. It would be fine to start with this as a base and then combine it with porous, quick draining ingredients, such as perlite, vermiculite, and gravel.
A very important part to have a good germination rate is
Soil is full of living things: bacteria, fungi, worms,eggs and insects and they like the same conditions that seeds to germinate,Humid and warm,That is why I sterilize all the soil even if is sealed in a bag,There are a few metods to do that ,I'm going to explaint tne one that I use
Microwave Oven Method
You also can sterilize soil in a microwave. Microwave soil for 1 minute per kilogram (2.2 pounds) on full power. Don't use metal containers and aluminum foil when using a microwave.
Fill clean a plastic container or polypropylene bag with very moist soil, perlite or soil mix medium Leave the top open and place in the center of a microwave oven. Treat for 2½ minutes . After treatment close the top of the bag and allow the soil to cool before removing.
Now you are ready to start sowing your seeds