Recently I have been wrapping the clean seed in a moist kitchen paper towel, slightly wet the paper towel then scrunch it around the seed. Then into a zip lock bag.
Best if the seed is clean of any fruit flesh.
This stops the seed drying out in open storage, and seems to wake it into pre germination.
There are also hot water treatments for prevention of seed infection by fungi, used by commercial growers.
Many Avocado rootstock growers plant the seed in tall pots or bags, rather than flats.
For those seed with a pointy end, plant point up, usually part in / part out of the mix.
For rounder seed, plant point up if you can tell, otherwise the top of the seed is where it was inside the fruit.
The many different methods will work.
Another approach was the one by my friend Dave, from Tropical Nth Qld.
He lives in a open side house in the jungle.
Basically he threw any Avocado seed as far as he could, out through the open kitchen window into the jungle.
He was originally American, and must have learnt to pitch at different bases, because last time I saw him he had quite a wide spread of fruiting Avocado trees coming along.