One way is to half-fill a glass with water, stick a couple of tooth-pics in there in an X-shape as a platform for the avocado seed/pit, then put the seed in there and wait for it to sprout. Be sure to put the point of the pit facing up. Most books do not say to do this due to low success rate, but this works very well for some people. Most sources discourage growing avocados from seed and suggest instead growing from either grafting or through budding or cuttings.