See The Garden, RHS February 2013, pp 58-62 for guidance on seed collection techniques.
This is when you scratch the surface of the seed coat. The easiest way to do this is to line the inside of a glass jar with a piece of rough sandpaper – add the seeds and shake a bit.
Some seeds can be soaked up to 6 hours before planting – such as narsturtium and peas.
This is when seeds are combined with moist potting compost and subjected to a period of cold or warm to simulate environmental conditions needed for germination.